S-adenosyl-L-methionine synthetase promoter and its use in expression of transgenic genes in plants

ABSTRACT

A constitutive plant S-adenosyl-L-methionine synthetase (SAMS) promoter and subfragments thereof and their use in promoting the expression of one or more heterologous nucleic acid fragments in plants are described.

This application is a Continuation of U.S. application Ser. No.11/746,688, filed May 10, 2007, now U.S. Pat. No. 7,834,242, issued Nov.16, 2010, which is a Continuation of U.S. application Ser. No.10/431,252, filed May 7, 2003, now U.S. Pat. No. 7,217,858, issued May15, 2007, which is a Continuation-in-Part of U.S. application Ser. No.09/464,528, filed Dec. 15, 1999, now abandoned, which claims the benefitof U.S. Provisional Application No. 60/113,045, filed Dec. 21, 1998. Theentire contents of which each are herein incorporated by reference.

FIELD OF THE INVENTION

This invention relates to a plant promoter, in particular, to anS-adenosyl-L-methionine synthetase (SAMS) promoter and subfragmentsthereof and their use in regulating the expression of at least oneheterologous nucleic acid fragment in plants.

BACKGROUND OF THE INVENTION

Recent advances in plant genetic engineering have opened new doors toengineer plants having improved characteristics or traits, such as,resistance to plant diseases, insect resistance, herbicidal resistance,enhanced stability or shelf-life of the ultimate consumer productobtained from the plants and improvement of the nutritional quality ofthe edible portions of the plant. Thus, a desired gene (or genes) from asource different than the plant, but engineered to impart different orimproved characteristics or qualities, can be incorporated into theplant's genome. This new gene (or genes) can then be expressed in theplant cell to exhibit the new trait or characteristic.

In order to obtain expression of the newly inserted gene in the plantcell, the proper regulatory signals must be present and be in the properlocation with respect to the gene. These regulatory signals include apromoter region, a 5′ non-translated leader sequence and a 3′transcription termination/polyadenylation sequence.

A promoter is a DNA sequence that directs cellular machinery of a plantto produce RNA from the contiguous coding sequence downstream (3′) ofthe promoter. The promoter region influences the rate, developmentalstage, and cell type in which the RNA transcript of the gene is made.The RNA transcript is processed to produce messenger RNA (mRNA) whichserves as a template for translation of the RNA sequence into the aminoacid sequence of the encoded polypeptide. The 5′ non-translated leadersequence is a region of the mRNA upstream of the protein coding regionthat may play a role in initiation and translation of the mRNA. The 3′transcription termination/polyadenylation signal is a non-translatedregion downstream of the protein coding region that functions in theplant cells to cause termination of the RNA transcript and the additionof polyadenylate nucleotides to the 3′ end of the RNA.

It has been shown that certain promoters are able to direct RNAsynthesis at a higher rate than others. These are called “strongpromoters”. Certain other promoters have been shown to direct RNAproduction at higher levels only in particular types of cells or tissuesand are often referred to as “tissue specific promoters”. In this group,many seed storage protein genes' promoters have been well characterizedand widely used, such as the phaseolin gene promoter of Phaseolusvulgaris, the helianthinin gene of sunflower, the β-conglycinin gene ofsoybean (Chen et al., (1989) Dev. Genet. 10, 112-122), the napin genepromoter of Brassica napus (Ellerstrom et al, (1996) Plant Mol. Biol.32, 1019-1027), the oleosin gene promoters of Brassica and Arabidopsis(Keddie et al, (1994) Plant Mol. Biol. 24, 327-340; Li, (1997) Texas A&MPh.D. dissertation, pp. 107-128; Plant et al, (1994) Plant Mol. Biol.25, 193-205). Another class of tissue specific promoters is describedin, U.S. Pat. No. 5,589,583, issued to Klee et al. on Dec. 31, 1996;these plant promoters are capable of conferring high levels oftranscription of chimeric genes in meristematic tissues and/or rapidlydividing cells. In contrast to tissue-specific promoters, “induciblepromoters” direct RNA production in response to certain environmentalfactors, such as heat shock, light, hormones, ion concentrations etc.(Espartero et al, (1994) Plant Mol. Biol. 25, 217-227; Gomez-Gomez andCarrasco, (1998) Plant Physiol. 117, 397-405; Holtorf et al, (1995)Plant Mol. Biol. 29, 637-646; MacDowell et al, (1996) Plant Physiol.111, 699-711; Mathur et al, (1992) Biochem. Biophys. Acta 1137, 338-348;Mett et al, (1996) Transgenic Res. 5, 105-113; Schoffl et al, (1989)Mol. Gen. Genet. 217, 246-253; Ulmasov et al, (1995) Plant Physiol. 108,919-927).

Promoters that are capable of directing RNA production in many or alltissues of a plant are called “constitutive promoters”. The idealconstitutive promoter should be able to drive gene expression in allcells of the organism throughout its development. Expression of manyso-called constitutive genes, such as actin (McDowell et al., (1996)Plant Physiol. 111, 699-711; Wang et al., (1992) Mol. Cell Biol. 12,3399-3406), and ubiquitin (Callis et al, (1990) J. Biol. Chem. 265,12486-12493; Rollfinke et al, (1998) Gene 211, 267-276) varies dependingon the tissue types and developmental stages of the plant. The mostwidely used constitutive promoter, the cauliflower mosaic virus 35Spromoter, also shows variations in activity in different plants and indifferent tissues of the same plant (Atanassova et al., (1998) PlantMol. Biol. 37, 275-285; Battraw and Hall, (1990) Plant Mol. Biol. 15,527-538; Holtorf et al., (1995) Plant Mol. Biol. 29, 637-646; Jeffersonet al., (1987) EMBO J. 6, 3901-3907; Wilmink et al., (1995) Plant Mol.Biol. 28, 949-955). The cauliflower mosaic virus 35S promoter is alsodescribed in U.S. Pat. No. 5,106,739. The tissue-specific expression andsynergistic interactions of sub-domains of the promoter of cauliflowermosaic virus are discussed in U.S. Pat. No. 5,097,025, which issued toBenfey et al. on Mar. 17, 1992. A Brassica promoter (hsp80) thatprovides for constitutive expression of heterologous genes in a widerange of tissues and organs is discussed in U.S. Pat. No. 5,612,472which issued to Wilson et al. on Mar. 18, 1997.

Some constitutive promoters have been used to drive expression ofselectable marker genes to facilitate isolation of transformed plantcells. U.S. Pat. No. 6,174,724 B1, issued to Rogers et al. on Jan. 16,2001, describes chimeric genes which can be used to create antibiotic orherbicide-resistant plants.

Since the patterns of expression of a chimeric gene (or genes)introduced into a plant are controlled using promoters, there is anongoing interest in the isolation and identification of novel promoterswhich are capable of controlling expression of a chimeric gene (orgenes).

SUMMARY OF THE INVENTION

This invention concerns an isolated nucleic acid fragment comprising apromoter wherein said promoter consists essentially of the nucleotidesequence set forth in SEQ ID NOs:6, 14, 15, or 16 or said promoterconsists essentially of a fragment or subfragment that is substantiallysimilar and functionally equivalent to the nucleotide sequence set forthin SEQ ID NOs:6, 14, 15, or 16.

In a second embodiment, this invention concerns a chimeric genecomprising at least one heterologous nucleic acid fragment operablylinked to the promoter of the invention.

In a third embodiment, this invention concerns plants containing thischimeric gene and seeds obtained from such plants.

In a fourth embodiment, this invention concerns a method of increasingor decreasing the expression of at least one heterologous nucleic acidfragment in a plant cell which comprises:

-   -   (a) transforming a plant cell with the chimeric gene described        above;    -   (b) growing fertile plants from the transformed plant cell of        step (a);    -   (c) selecting plants containing the transformed plant cell        wherein the expression of the heterologous nucleic acid fragment        is increased or decreased.

In a fifth embodiment, this invention concerns an isolated nucleic acidfragment comprising a constitutive plant SAMS promoter.

In a sixth embodiment, this invention concerns a recombinant DNAconstruct comprising a first isolated nucleic acid fragment encoding apolypeptide with acetolactate synthase activity, wherein saidpolypeptide has one or both of the following mutations, an amino acidother than proline in a conserved amino acid region G-Q-V-P (SEQ IDNO:31) and an amino acid other than tryptophan in a conserved amino acidregion G-M-V-V/M-Q-W-E-D-R-F (SEQ ID NO:32), and said polypeptide isresistant to at least one inhibitor of acetolactate synthase, operablylinked to a second isolated nucleic acid fragment, having constitutivepromoter activity in a plant, selected from the group consisting of:

a) an isolated nucleic acid fragment comprising the nucleic acidsequence of SEQ ID NO:6;

b) an isolated nucleic acid fragment comprising the nucleic acidsequence of SEQ ID NO:14;

c) an isolated nucleic acid fragment comprising nucleotides 4-644 of SEQID NO:6;

d) an isolated nucleic acid fragment comprising nucleotides 1-1496 ofSEQ ID NO:14;

e) an isolated nucleic acid fragment comprising a subfragment of SEQ IDNO:6, wherein the subfragment has constitutive promoter activity in aplant;

f) an isolated nucleic acid fragment comprising a subfragment of SEQ IDNO:14, wherein the subfragment has constitutive promoter activity in aplant; and

g) an isolated nucleic acid fragment, having constitutive promoteractivity in a plant, which can hybridize under stringent conditions withany of the isolated nucleic acid fragments set forth in (a) through (f).

In a seventh embodiment, this invention concerns a method for selectionof a transformed plant cell having resistance to at least one inhibitorof acetolactate synthase which comprises:

(a) transforming a plant cell with the recombinant DNA construct of thesixth embodiment;

(b) growing the transformed plant cell of step (a) in the presence of aneffective amount of at least one inhibitor of acetolactate synthase; and

(c) selecting a transformed plant cell wherein said transformed plantcell is resistant to at least one inhibitor of acetolactate synthase.

In an eighth embodiment, this invention concerns a method for producinga plant having resistance to at least one inhibitor of acetolactatesynthase which comprises:

(a) transforming a plant cell with the recombinant DNA construct of thesixth embodiment;

(b) growing at least one fertile transformed plant from the transformedplant cell of step (a); and

(c) selecting a transformed plant wherein said transformed plant isresistant to at least one inhibitor of acetolactate synthase.

BRIEF DESCRIPTION OF THE DRAWINGS AND SEQUENCES

The invention can be more fully understood from the following detaileddescription, the drawings and the Sequence Descriptions that form a partof this application. The Sequence Descriptions contain the three lettercodes for amino acids as defined in 37 C.F.R. §§1.821-1.825, which areincorporated herein by reference.

SEQ ID NO:1 is the nucleotide sequence comprising the entire cDNA insertin clone s2.12b06 which encodes a soybean S-adenosyl-L-methioninesynthetase protein.

SEQ ID NO:2 is the nucleotide sequence comprising a soybeanS-adenosyl-L-methionine synthetase genomic DNA fragment.

SEQ ID NO:3 is the nucleotide sequence of a portion of the cDNA insertin clone srr1c.pk002.b21 encoding a portion of a soybeanS-adenosyl-L-methionine synthetase protein.

SEQ ID NO:4 is a 32 base oligonucleotide primer, designated sam-5, usedto amplify the soybean S-adenosyl-L-methionine synthetase promoterregion via PCR.

SEQ ID NO:5 is a 24 base oligonucleotide primer, designated sam-6, usedto amplify the soybean S-adenosyl-L-methionine synthetase promoterregion via PCR.

SEQ ID NO:6 is the nucleotide sequence comprising a soybeanS-adenosyl-L-methionine synthetase promoter fragment produced via PCRusing primers sam-5 (SEQ ID NO:4) and sam-6 (SEQ ID NO:5).

SEQ ID NO:7 is a 22 base oligonucleotide primer, designated sam-9, usedto amplify the soybean S-adenosyl-L-methionine synthetase promoterregion via PCR.

SEQ ID NO:8 is a 19 base oligonucleotide primer, designated atps-9, usedto amplify a chimeric gene comprising a SAMS promoter fragment and aportion of the ATP sulfurylase (ATPS) gene via PCR.

SEQ ID NO:9 is a 21 base oligonucleotide primer, designated cgs-8, usedto amplify a chimeric gene comprising a SAMS promoter and a portion ofthe cystathionine-γ-synthase 1 (CGS1) gene via PCR.

SEQ ID NO:10 is a 20 base oligonucleotide antisense primer, designatedatps-4, used to amplify the ATP sulfurylase transcript via RT-PCR.

SEQ ID NO:11 is a 21 base oligonucleotide antisense primer, designatedcgs-10, used to amplify the cystathionine-γ-synthase 1 transcript viaRT-PCR.

SEQ ID NO:12 is a 20 base oligonucleotide primer, designated atps-3,used to amplify an ATP sulfurylase cDNA via PCR.

SEQ ID NO:13 is a 23 base oligonucleotide primer, designated cgs-9, usedto amplify a cystathionine-γ-synthase 1 cDNA via PCR.

SEQ ID NO:14 is a 2165 nucleotide sequence comprising a soybeanS-adenosyl-L-methionine synthetase genomic DNA fragment which starts atthe 5′ end of SEQ ID NO:2, and ends at the ATG translation start codonof the S-adenosyl-L-methionine synthetase.

SEQ ID NO:15 is a 1574 nucleotide sequence comprising a DNA fragmentwhich starts at the 5′ end of SEQ ID NO:2, and ends at the ATGtranslation start codon of the S-adenosyl-L-methionine synthetase, andwherein a 591 nucleotide intron sequence has been removed.

SEQ ID NO:16 is a 719 nucleotide sequence comprising a DNA fragmentwhich starts at nucleotide 4 of SEQ ID NO:6, and ends at the ATGtranslation start codon of the S-adenosyl-L-methionine synthetase, andwherein a 591 nucleotide intron sequence has been removed.

SEQ ID NO:17 is a 6975 nucleotide sequence comprising plasmid pMH40Δ.

SEQ ID NO:18 is a 3985 nucleotide sequence comprising a SAMSpromoter::GUS::3′ Nos DNA fragment present in plasmid pZSL11.

SEQ ID NO:19 is a 3684 nucleotide sequence comprising a SAMSpromoter:ATPS::3′ Nos DNA fragment.

SEQ ID NO:20 is a 3963 nucleotide sequence comprising a SAMSpromoter::CGS1::3′ Nos DNA fragment.

SEQ ID NO:21 is a 4827 nucleotide sequence from pZSL12 comprising a2.1-kb SAMS promoter::GUS::3′ Nos DNA fragment.

SEQ ID NO:22 is a 3939 nucleotide sequence from pZSL13 comprising a1.3-kb SAMS promoter::herbicide-resistant soybean acetolactate synthase(ALS) coding region::3′ soybean ALS DNA fragment.

SEQ ID NO:23 is the amino acid sequence of the herbicide-resistantsoybean ALS protein encoded by SEQ ID NO:22.

SEQ ID NO:24 is a 5408 nucleotide sequence from pZSL14 comprising a2.1-kb SAMS promoter::herbicide-resistant Arabidopsis ALS codingregion::3′Arabidopsis ALS DNA fragment.

SEQ ID NO:25 is the amino acid sequence of the herbicide-resistantArabidopsis ALS protein encoded by SEQ ID NO:24.

SEQ ID NO:26 is the amino acid sequence of the tobaccoherbicide-sensitive SURA (ALS I) acetolactate synthase protein (NCBIGeneral Identifier No. 124367).

SEQ ID NO:27 is the amino acid sequence of the tobaccoherbicide-sensitive SURB (ALS II) acetolactate synthase protein (NCBIGeneral Identifier No. 124369).

SEQ ID NO:28 is the amino acid sequence of the Brassica napusherbicide-sensitive acetolactate synthase 3 protein (NCBI GeneralIdentifier No. 320131).

SEQ ID NO:29 is the amino acid sequence of the Arabidopsis thalianaherbicide-sensitive acetolactate synthase protein (NCBI GeneralIdentifier No. 124372).

SEQ ID NO:30 is the amino acid sequence of the soybeanherbicide-sensitive acetolactate synthase protein.

FIGS. 1A and 1B depict Southern hybridization analyses of SAMS genes.Soybean genomic DNA was digested with BamHI, EcoRI, HindIII, KpnI, andSacI, and then the blot was hybridized with a full length SAMS cDNA (SEQID NO:1) probe in FIG. 1A or with a SAMS promoter fragment (SEQ ID NO:6)probe in FIG. 1B.

FIG. 2 depicts a SAMS genomic DNA sequence (SEQ ID NO:2) and thealignment of the overlapping region with SAMS cDNA sequence (SEQ IDNO:1). The 2336 bp SAMS genomic DNA sequence has a 191 bp region alignedwith the 5′ end sequence of the SAMS cDNA with six mismatches. Theregion used to make the SAMS promoter by adding the NcoI site at its 3′end is underlined. The translation start codon is in bold.

FIG. 3 depicts the structure of the SAMS::GUS expression cassette. TheSAMS promoter was cloned into pMH40Δ to replace its 35S promoter. Thestructure of the resulted SAMS::GUS construct was generated by VectorNTI™ software (InforMax, Inc., North Bethesda, Md.).

FIG. 4 depicts a histochemical GUS expression analysis of transgenicArabidopsis plants harboring the SAMS::GUS expression cassette.Arabidopsis tissues were incubated at 37° C. with X-Gluc overnight anddehydrated with ethanol. (A) Flower buds; (B) leaf; (C) Inflorescencestem and a cauline leaf; (D, E, F) developing siliques; (G) Developingseeds and embryos. All of the seeds were derived from GUS-positivesiliques. Genetic segregation of the GUS gene was demonstrated by theblue funiculus of the white seed in the right upper corner.

FIG. 5 depicts a fluorometric GUS expression assay of transgenicArabidopsis plants harboring the SAMS::GUS expression cassette. Triplesamples of flowers, leaves, stems, siliques coats, young seeds, mediumseeds, old seeds, and dry seeds collected from SAMS::GUS transgenicArabidopsis plants were assayed for GUS activity. The graph wasgenerated by Microsoft Excel and the standard deviation is indicated bythe upper part of each column.

FIG. 6 depicts a histochemical GUS transient expression analysis of SAMSpromoter in corn. The pZSL11 (SAMS::GUS) or the pMH40Δ (35S::GUS)plasmid DNA was delivered into corn callus (A, C) or leaf discs (B, D),and the GUS activity was detected by incubation with X-Gluc overnight at37° C. (A, B) Transformed with pZSL11 DNA; (C, D) Transformed withpMH40Δ DNA.

FIGS. 7(A) and 7(B) depict the presence and expression of transgenicsoybean ATPS and CGS1 genes controlled by the SAMS promoter intransgenic Arabidopsis plants. FIG. 7(A) is a PCR analysis. Genomic DNAof ten transgenic Arabidopsis plants (1 to 10), wild type Arabidopsis(a), wild type soybean (s), and plasmid DNA of SAMS::CGS1 or SAMS::ATPSin binary vectors (p) were used as templates in PCR with gene-specificprimers. PCR of ten SAMS::CGS1 transgenic plants with primer sam-9 whichis specific to SAMS promoter, and primer cgs-8 which is specific tosoybean CGS1 (upper). PCR of ten SAMS::ATPS transgenic plants withprimer sam-9 which is specific to SAMS promoter, and primer atps-1 whichis specific to soybean ATPS gene (lower). FIG. 7(B) is an RT-PCRanalysis. Total leaf RNA of ten transgenic Arabidopsis plants (1 to 10),wild type Arabidopsis (a), and wild type soybean (s) were used astemplates in RT-PCR with gene-specific primers. First strand cDNA wassynthesized from a gene-specific antisense primer with reversetranscriptase, and then the first strand cDNA was amplified by PCR withboth sense and antisense primers. RT-PCR of ten SAMS::CGS1 transgenicplants with primers, cgs-9 (sense) and cgs-10 (antisense), specific tosoybean CGS1 gene (upper). RT-PCR of ten SAMS::ATPS transgenic plantswith primers, atps-3 (sense) and atps-4 (antisense), specific to soybeanATPS gene (lower).

FIG. 8 depicts induction of SAMS promoter activity by methionine. Seedsof ten transgenic Arabidopsis lines transformed with SAMS::GUS constructwere germinated on filter papers soaked with H₂O, 1× Murashige and Skoogsalt, 0.01 mM, and 1 mM methionine. Ten days old seedlings wereharvested and assayed for GUS activity. The solid bar and hollow barindicate, respectively, the average and the standard variation of threesamples for each treatment.

FIG. 9 depicts a northern hybridization. Soybean total RNAs from leaves,roots, stems, young seeds, medium seeds, old seeds, and pod coats (L, R,S, Y, M, O, and P) were used to make the RNA blot which was hybridizedwith a full length SAMS cDNA (SEQ ID NO:1) probe.

FIGS. 10A, 10B and 10C depict an amino acid sequence alignment of thefollowing herbicide-sensitive acetolactate synthase (ALS) proteins: atobacco SURB (ALS II) protein (SEQ ID NO:27; NCBI General Identifier No.124369); a Brassica napus ALS3 (AHAS3) protein (SEQ ID NO:28; NCBIGeneral Identifier No. 320131); an Arabidopsis thaliana ALS protein (SEQID NO:29; NCBI General Identifier No. 124372); and a soybean ALS protein(SEQ ID NO:30). The numbering for the consensus amino acid sequence isshown below. The numbering for each ALS sequence is shown to the left ofeach row and to the right of the final row. Amino acids which areconserved among all four sequences are indicated with an asterisk abovethe amino acid residue. Shown below the four sequences are sevenconserved amino acid regions, subfragments “A” through “G” described inU.S. Pat. No. 5,013,659, in which changes in particular amino acidresidues can lead to herbicide resistance. A caret below the lysineresidue at consensus amino acid position 98 indicates the start of themature ALS polypeptide. The chloroplast transit peptide for each ALSprotein is within consensus amino acid region 1-97.

FIG. 11 depicts GUS expression in soybean embryogenic cell linestransformed with pZSL11 or pZSL12.

FIG. 12 depicts GUS expression in soybean tissues transformed withpZSL11.

DETAILED DESCRIPTION OF THE INVENTION

In the context of this disclosure, a number of terms shall be utilized.

As used herein, an “isolated nucleic acid fragment” is a polymer ofribonucleotides (RNA) or deoxyribonucleotides (DNA) that is single- ordouble-stranded, optionally containing synthetic, non-natural or alterednucleotide bases. An isolated nucleic acid fragment in the form of DNAmay be comprised of one or more segments of cDNA, genomic DNA orsynthetic DNA.

The terms “subfragment that is functionally equivalent” and“functionally equivalent subfragment” are used interchangeably herein.These terms refer to a portion or subsequence of an isolated nucleicacid fragment in which the ability to alter gene expression or produce acertain phenotype is retained whether or not the fragment or subfragmentencodes an active enzyme. For example, the fragment or subfragment canbe used in the design of chimeric genes to produce the desired phenotypein a transformed plant. Chimeric genes can be designed for use inco-suppression or antisense by linking a nucleic acid fragment orsubfragment thereof, whether or not it encodes an active enzyme, in theappropropriate orientation relative to a plant promoter sequence.

The terms “substantially similar” and “corresponding substantially” asused herein refer to nucleic acid fragments wherein changes in one ormore nucleotide bases does not affect the ability of the nucleic acidfragment to mediate gene expression or produce a certain phenotype.These terms also refer to modifications of the nucleic acid fragments ofthe instant invention such as deletion or insertion of one or morenucleotides that do not substantially alter the functional properties ofthe resulting nucleic acid fragment relative to the initial, unmodifiedfragment. It is therefore understood, as those skilled in the art willappreciate, that the invention encompasses more than the specificexemplary sequences.

Moreover, the skilled artisan recognizes that substantially similarnucleic acid sequences encompassed by this invention are also defined bytheir ability to hybridize, under stringent or moderately stringentconditions (for example, 0.5×SSC, 0.1% SDS, 60° C.) with the sequencesexemplified herein, or to any portion of the nucleotide sequencesreported herein and which are functionally equivalent to the promoter ofthe invention. Stringent hybridization conditions using 50% formamidecan be found in Current Protocols in Molecular Biology, edited by F. M.Ausubel, R. Brent, R. E. Kingston, D. D. Moore, J. G. Seidman, J. A.Smith, and K. Struhl, John Wiley & Sons, New York, 1992. A formamidestringent hybridization buffer can contain the following: 50% formamide;5×SSC; 20 mM Tris-Cl, pH 7.6; 1×Denhardt's solution; 10% dextransulfate; and 1% SDS. Hybridization can occur at 42° C. in the abovebuffer with an overnight incubation. Washes can be done in 2×SSC, 0.1%SDS, for 15 minutes and then three 15 minutes washes in 0.2×SSC, 0.1%SDS, before exposure to film. A 100×Denhardt′ s solution can be preparedin the following manner: 2 g bovine serum albumin; 2 g Ficoll 400; 2 gPolyvinylpyrrolidone; add approximately 50 ml of distilled water; mix todissolve; make up to a final volume of 100 ml and store at −20° C.Alternatively, stringent hybridization conditions can use DIG Easy Hybbuffer (Roche Diagnostics Corp.). DIG Easy Hyb is non-toxic and does notcontain formamide, yet the hybridization temperature should becalculated with the same equation that is used for buffer containing 50%formamide. A hybridization temperature of 45° C., 55° C., or any integerdegree between 45° C. and 55° C., can be used for hybridization ofhomologous probes to plant genomic DNA. Preferred substantially similarnucleic acid sequences encompassed by this invention are those sequencesthat are 80% identical to the nucleic acid fragments reported herein orwhich are 80% identical to any portion of the nucleotide sequencesreported herein. More preferred are nucleic acid fragments which are 90%identical to the nucleic acid sequences reported herein, or which are90% identical to any portion of the nucleotide sequences reportedherein. Most preferred are nucleic acid fragments which are 95%identical to the nucleic acid sequences reported herein, or which are95% identical to any portion of the nucleotide sequences reportedherein. Useful examples of preferred percent identities are any integerpercentage from 80% to 100%. Sequence alignments and percent similaritycalculations may be determined using the Megalign program of theLASARGENE bioinformatics computing suite (DNASTAR Inc., Madison, Wis.).Multiple alignment of the sequences are performed using the Clustalmethod of alignment (Higgins and Sharp (1989) CABIOS. 5:151-153) withthe default parameters (GAP PENALTY=10, GAP LENGTH PENALTY=10). Defaultparameters for pairwise alignments and calculation of percent identityof protein sequences using the Clustal method are KTUPLE=1, GAPPENALTY=3, WINDOW=5 and DIAGONALS SAVED=5. For nucleic acids theseparameters are GAP PENALTY=10, GAP LENGTH PENALTY=10, KTUPLE=2, GAPPENALTY=5, WINDOW=4 and DIAGONALS SAVED=4. A “substantial portion” of anamino acid or nucleotide sequence comprises enough of the amino acidsequence of a polypeptide or the nucleotide sequence of a gene to affordputative identification of that polypeptide or gene, either by manualevaluation of the sequence by one skilled in the art, or bycomputer-automated sequence comparison and identification usingalgorithms such as BLAST (Altschul, S. F., et al., (1993) J. Mol. Biol.215:403-410) and Gapped Blast (Altschul, S. F. et al., (1997) NucleicAcids Res. 25:3389-3402).

“Gene” refers to a nucleic acid fragment that expresses a specificprotein, including regulatory sequences preceding (5′ non-codingsequences) and following (3′ non-coding sequences) the coding sequence.“Native gene” refers to a gene as found in nature with its ownregulatory sequences. “Chimeric gene” refers to any gene that is not anative gene, comprising regulatory and coding sequences that are notfound together in nature. Accordingly, a chimeric gene may compriseregulatory sequences and coding sequences that are derived fromdifferent sources, or regulatory sequences and coding sequences derivedfrom the same source, but arranged in a manner different than that foundin nature. “Endogenous gene” refers to a native gene in its naturallocation in the genome of an organism. A “foreign” gene refers to a genenot normally found in the host organism, but that is introduced into thehost organism by gene transfer. Foreign genes can comprise native genesinserted into a non-native organism, or chimeric genes.

A “heterologous nucleic acid fragment” refers to a nucleic acid fragmentcomprising a nucleic acid sequence that is different from the nucleicacid sequence comprising the plant promoter of the invention.

“Coding sequence” refers to a DNA sequence that codes for a specificamino acid sequence. “Regulatory sequences” refer to nucleotidesequences located upstream (5′ non-coding sequences), within, ordownstream (3′ non-coding sequences) of a coding sequence, and whichinfluence the transcription, RNA processing or stability, or translationof the associated coding sequence. Regulatory sequences may include, butare not limited to, promoters, translation leader sequences, introns,and polyadenylation recognition sequences.

“Promoter” refers to a DNA sequence capable of controlling theexpression of a coding sequence or functional RNA. The promoter sequenceconsists of proximal and more distal upstream elements, the latterelements often referred to as enhancers. Accordingly, an “enhancer” is aDNA sequence which can stimulate promoter activity and may be an innateelement of the promoter or a heterologous element inserted to enhancethe level or tissue-specificity of a promoter. Promoters may be derivedin their entirety from a native gene, or be composed of differentelements derived from different promoters found in nature, or evencomprise synthetic DNA segments. It is understood by those skilled inthe art that different promoters may direct the expression of a gene indifferent tissues or cell types, or at different stages of development,or in response to different environmental conditions. Promoters whichcause a gene to be expressed in most cell types at most times arecommonly referred to as “constitutive promoters”. In particular, aconstitutive promoter refers to a promoter which causes a gene to beexpressed in at least the following types of plant tissue: leaf, root,stem, seed and callus. New promoters of various types useful in plantcells are constantly being discovered; numerous examples may be found inthe compilation by Okamuro and Goldberg (1989, Biochemistry of Plants15:1-82). It is further recognized that since in most cases the exactboundaries of regulatory sequences have not been completely defined, DNAfragments of some variation may have identical promoter activity. An“intron” is an intervening sequence in a gene that is transcribed intoRNA but is then excised in the process of generating the mature mRNA.The term is also used for the excised RNA sequences. An “exon” is aportion of the sequence of a gene that is transcribed and is found inthe mature messenger RNA derived from the gene, but is not necessarily apart of the sequence that encodes the final gene product.

The “translation leader sequence” refers to a DNA sequence locatedbetween the promoter sequence of a gene and the coding sequence. Thetranslation leader sequence is present in the fully processed mRNAupstream of the translation start sequence. The translation leadersequence may affect processing of the primary transcript to mRNA, mRNAstability or translation efficiency. Examples of translation leadersequences have been described (Turner, R. and Foster, G. D. (1995)Molecular Biotechnology 3:225).

The “3′ non-coding sequences” refer to DNA sequences located downstreamof a coding sequence and include polyadenylation recognition sequencesand other sequences encoding regulatory signals capable of affectingmRNA processing or gene expression. The polyadenylation signal isusually characterized by affecting the addition of polyadenylic acidtracts to the 3′ end of the mRNA precursor. The use of different 3′non-coding sequences is exemplified by Ingelbrecht et al., (1989) PlantCell 1:671-680.

“RNA transcript” refers to a product resulting from RNApolymerase-catalyzed transcription of a DNA sequence. When an RNAtranscript is a perfect complementary copy of a DNA sequence, it isreferred to as a primary transcript or it may be a RNA sequence derivedfrom posttranscriptional processing of a primary transcript and isreferred to as a mature RNA. “Messenger RNA” (“mRNA”) refers to RNA thatis without introns and that can be translated into protein by the cell.“cDNA” refers to a DNA that is complementary to and synthesized from anmRNA template using the enzyme reverse transcriptase. The cDNA can besingle-stranded or converted into the double-stranded by using theklenow fragment of DNA polymerase I. “Sense” RNA refers to RNAtranscript that includes mRNA and so can be translated into proteinwithin a cell or in vitro. “Antisense RNA” refers to a RNA transcriptthat is complementary to all or part of a target primary transcript ormRNA and that blocks expression or transcripts accumulation of a targetgene (U.S. Pat. No. 5,107,065). The complementarity of an antisense RNAmay be with any part of the specific gene transcript, i.e. at the 5′non-coding sequence, 3′ non-coding sequence, introns, or the codingsequence. “Functional RNA” refers to antisense RNA, ribozyme RNA, orother RNA that may not be translated but yet has an effect on cellularprocesses.

“Sense” RNA refers to RNA transcript that includes the mRNA and so canbe translated into protein by the cell. “Antisense RNA” refers to a RNAtranscript that is complementary to all or part of a target primarytranscript or mRNA and that blocks the expression of a target gene (U.S.Pat. No. 5,107,065). The complementarity of an antisense RNA may be withany part of the specific gene transcript, i.e., at the 5′ non-codingsequence, 3′ non-coding sequence, introns, or the coding sequence.“Functional RNA” refers to antisense RNA, ribozyme RNA, or other RNAthat may not be translated but yet has an effect on cellular processes.

The term “operably linked” refers to the association of nucleic acidsequences on a single nucleic acid fragment so that the function of oneis affected by the other. For example, a promoter is operably linkedwith a coding sequence when it is capable of affecting the expression ofthat coding sequence (i.e., that the coding sequence is under thetranscriptional control of the promoter). Coding sequences can beoperably linked to regulatory sequences in sense or antisenseorientation.

The term “expression”, as used herein, refers to the production of afunctional end-product. Expression or overexpression of a gene involvestranscription of the gene and translation of the mRNA into a precursoror mature protein. “Antisense inhibition” refers to the production ofantisense RNA transcripts capable of suppressing the expression of thetarget protein. “Overexpression” refers to the production of a geneproduct in transgenic organisms that exceeds levels of production innormal or non-transformed organisms. “Co-suppression” refers to theproduction of sense RNA transcripts capable of suppressing theexpression or transcript accumulation of identical or substantiallysimilar foreign or endogenous genes (U.S. Pat. No. 5,231,020). Themechanism of co-suppression may be at the DNA level (such as DNAmethylation), at the transcriptional level, or at post-transcriptionallevel.

“Altered expression” refers to the production of gene product(s) intransgenic organisms in amounts or proportions that differ significantlyfrom the amount of the gene product(s) produced by the correspondingwild-type organisms.

“Stable transformation” refers to the transfer of a nucleic acidfragment into a genome of a host organism, including both nuclear andorganellar genomes, resulting in genetically stable inheritance. Incontrast, “transient transformation” refers to the transfer of a nucleicacid fragment into the nucleus, or DNA-containing organelle, of a hostorganism resulting in gene expression without integration or stableinheritance. Host organisms containing the transferred nucleic acidfragments are referred to as “transgenic” or “transformed” organisms.The preferred method of cell transformation of rice, corn and othermonocots is the use of particle-accelerated or “gene gun” transformationtechnology (Klein et al, (1987) Nature (London) 327:70-73; U.S. Pat. No.4,945,050), or an Agrobacterium-mediated method using an appropriate Tiplasmid containing the transgene (Ishida Y. et al, 1996, Nature Biotech.14:745-750).

“Regeneration medium” (RM) promotes differentiation of totipotentembryogenic plant tissues into shoots, roots and other organizedstructures and eventually into plantlets that can be transferred tosoil.

“Plant culture medium” is any medium used in the art for supportingviability and growth of a plant cell or tissue, or for growth of wholeplant specimens. Such media commonly include, but are not limited to,macronutrient compounds providing nutritional sources of nitrogen,phosphorus, potassium, sulfur, calcium, magnesium, and iron;micronutrients, such as boron, molybdenum, manganese, cobalt, zinc,copper, chlorine, and iodine; carbohydrates; vitamins; phytohormones;selection agents; and may include undefined components, including, butnot limited to, casein hydrolysate, yeast extract, and activatedcharcoal. The medium may be either solid or liquid.

“Plant cell” is the structural and physiological unit of plants,consisting of a protoplast and the cell wall.

“Plant tissue” is a group of plant cells organized into a structural andfunctional unit.

The term “recombinant” means, for example, that a nucleic acid sequenceis made by an artificial combination of two otherwise separated segmentsof sequence, e.g., by chemical synthesis or by the manipulation ofisolated nucleic acids by genetic engineering techniques. A “recombinantDNA construct” comprises an isolated polynucleotide operably linked toat least one regulatory sequence. The term also embraces an isolatedpolynucleotide comprising a region encoding all or part of a functionalRNA and at least one of the naturally occurring regulatory sequencesdirecting expression in the source (e.g., organism) from which thepolynucleotide was isolated, such as, but not limited to, an isolatedpolynucleotide comprising a nucleotide sequence encoding a herbicideresistant target gene and the corresponding promoter and 3′ endsequences directing expression in the source from which sequences wereisolated. The terms “recombinant DNA construct”, “recombinant construct”and “chimeric gene” are used interchangeably herein.

A “transgene” is a recombinant DNA construct that has been introducedinto the genome by a transformation procedure.

“Selection agent” refers to a compound which is toxic to non-transformedplant cells and which kills non-transformed tissues when it isincorporated in the culture medium in an “effective amount”, i.e., anamount equal to or greater than the minimal amount necessary to killnon-transformed tissues. Cells can be transformed with an appropriategene, such that expression of that transgene confers resistance to thecorresponding selection agent, via de-toxification or another mechanism,so that these cells continue to grow and are subsequently able toregenerate plants. The gene conferring resistance to the selection agentis termed the “selectable marker gene”, “selectable marker” or“resistance gene”. Transgenic cells that lack a functional selectablemarker gene will be killed by the selection agent. Selectable markergenes include genes conferring resistance to herbicidal compounds.Herbicide resistance genes generally code for a modified target proteininsensitive to the herbicide or for an enzyme that degrades ordetoxifies the herbicide in the plant before it can act (DeBlock et al.,1987, EMBO J. 6:2513-2518, DeBlock et al., 1989, Plant Physiol., 91:691-704). For example, resistance to glyphosate or sulfonylureaherbicides has been obtained by using genes coding for mutant versionsof the target enzymes, 5-enolpyruvylshikimate-3-phosphate synthase(EPSPS) and acetolactate synthase (ALS), respectively. Resistance toglufosinate ammonium, bromoxynil and 2,4-dichlorophenoxyacetic acid(2,4-D) has been obtained by using bacterial genes encodingphosphinothricin acetyltransferase, a nitrilase, or a2,4-dichlorophenoxyacetate monooxygenase, respectively, which detoxifythe respective herbicide. “Sulfonylurea herbicides” include but are notlimited to Rimsulfuron, Nicosulfuron, Classic, and (just. A specificselection agent may have one or more corresponding selectable markergenes. Likewise, a specific selectable marker gene may have one or morecorresponding selection agents. It is appreciated by one skilled in theart that a selection agent may not be toxic to all plant species or toall cell types within a given plant. For a plant species susceptible toa given selection agent, it is also appreciated that resistance cells,tissues or whole plants may be obtained independent of thetransformation process, e.g., through chemical mutagenesis of the targetgene or gene amplification of the target gene during tissue culture.

Examples of suitable selection agents, include but are not limited to,cytotoxic agents such as hygromycin, sulfonylurea herbicides such asNicosulfuron and Rimsulfuron, and other herbicides which act byinhibition of the enzyme acetolactate synthase (ALS), glyphosate,bialaphos and phosphinothricin (PPT). It is also possible to usepositive selection marker systems such as phospho-mannose isomerase andsimilar systems which confer positive growth advantage to transgeniccells.

Any regenerable plant tissue can be used in accordance with the presentinvention. Regenerable plant tissue generally refers to tissue which canbe regenerated into a differentiated plant. For example, such tissuescan include calluses and/or somatic embryos derived from whole zygoticembryos, isolated scutella, anthers, inflorescences and leaf andmeristematic tissues.

In order to identify transformed tissues, cultures may be exposed to aselection agent appropriate to a selectable marker gene included in therecombinant DNA construct used for transformation. The selection agentmay be supplied during the callus induction or proliferation phases ofculture, or may be supplied during culture on regeneration medium.Single, or more commonly multiple passages of selection may be applied.Even when a resistance gene is expressed in transformed tissues it iscommon for the application of selection to reduce the efficiency offormation of regenerable tissue from transformed cells (e.g. to reducethe frequency of somatic embryogenesis). Thus, it is preferable tosupply the selection agent during the regeneration phase of culturerather than during the induction phase in order to increase theefficiency of formation of regenerable tissue from transformed cells.

Standard recombinant DNA and molecular cloning techniques used hereinare well known in the art and are described more fully in Sambrook, J.,Fritsch, E. F. and Maniatis, T., Molecular Cloning: A Laboratory Manual;Cold Spring Harbor Laboratory Press, Cold Spring Harbor, 1989(hereinafter “Sambrook et al., 1989”) or Ausubel, F. M., Brent, R.,Kingston, R. E., Moore, D. D., Seidman, J. G., Smith, J. A. and Struhl,K. (eds.), Current Protocols in Molecular Biology, John Wiley and Sons,New York, 1990 (hereinafter “Ausubel et al., 1990”).

“PCR” or “Polymerase Chain Reaction” is a technique for the synthesis oflarge quantities of specific DNA segments, consists of a series ofrepetitive cycles (Perkin Elmer Cetus Instruments, Norwalk, Conn.).Typically, the double stranded DNA is heat denatured, the two primerscomplementary to the 3′ boundaries of the target segment are annealed atlow temperature and then extended at an intermediate temperature. Oneset of these three consecutive steps comprises a cycle.

An “expression construct” is a plasmid vector or a subfragment thereofcomprising the instant recombinant DNA construct. The choice of plasmidvector is dependent upon the method that will be used to transform hostplants. The skilled artisan is well aware of the genetic elements thatmust be present on the plasmid vector in order to successfullytransform, select and propagate host cells containing the recombinantDNA construct. The skilled artisan will also recognize that differentindependent transformation events will result in different levels andpatterns of expression (Jones et al., (1985) EMBO J. 4:2411-2418; DeAlmeida et al., (1989) Mol. Gen. Genetics 218:78-86), and thus thatmultiple events must be screened in order to obtain lines displaying thedesired expression level and pattern. Such screening may be accomplishedby Southern analysis of DNA, Northern analysis of mRNA expression,Western analysis of protein expression, or phenotypic analysis. Theterms “expression construct”, “expression cassette” and “recombinantexpression construct” are used interchangeably herein.

Although the SAMS enzyme is present in most plant cell types, no SAMSpromoter capable of driving gene expression in most or all plant celltypes has been described. Previous studies indicated that plants containmultiple SAMS genes which are differentially expressed in response tovarious stresses (Schroder et al. (1997) Plant Mol. Biol. 33:211-222). ASAMS promoter that is preferentially active in a particular tissue type,i.e. vascular (Peleman et al., (1989) Plant Cell 1, 81-93; Mijnsbruggeet al., (1996) Plant Cell Physiol. 37, 1108-1115), was also known.However, it was not possible to predict, before the studies reportedherein, whether any SAMS gene was controlled by a constitutive promoter.It is demonstrated herein that constitutive SAMS promoters do, in fact,exist in plants, and that such promoters can be readily isolated andused by one skilled in the art.

This invention concerns an isolated nucleic acid fragment comprising aconstitutive plant SAMS promoter. This invention also concerns anisolated nucleic acid fragment comprising a promoter wherein saidpromoter consists essentially of the nucleotide sequence set forth inSEQ ID NOs:6, 14, 15 or 16 or said promoter consists essentially of afragment or subfragment that is substantially similar and functionallyequivalent to the nucleotide sequence set forth in SEQ ID NOs:6, 14, 15or 16. A nucleic acid fragment that is functionally equivalent to theinstant SAMS promoter is any nucleic acid fragment that is capable ofcontrolling the expression of a coding sequence or functional RNA in asimilar manner to the SAMS promoter. The expression patterns of the SAMSpromoter are defined in the following paragraphs.

Northern-blot hybridization experiments indicated that SAMS genetranscripts are present in a variety of soybean tissues and that theabundance of SAMS gene transcripts does not differ greatly from tissueto tissue (FIG. 9 and Example 3). Strong expression of the SAMS gene wasalso inferred by the high frequency of occurrences of cDNA sequenceswith homology to SAMS (ESTs) in a soybean cDNA sequence database createdby sequencing random cDNAs from libraries prepared from many differentsoybean tissues. ESTs encoding SAMS can be easily identified byconducting BLAST (Basic Local Alignment Search Tool; Altschul, S. F., etal., (1993) J. Mol. Biol. 215:403-410) searches for similarity tosequences contained in the BLAST “nr” database, e.g., SAMS from Oryzasativa (EMBL Accession No. Z26867) or SEQ ID NO:1 provided herein. SAMShomologs were among the most abundant classes of cDNAs found in thesoybean libraries. This indicated that SAMS was a highly expressed genein most soybean cell types. The data obtained from sequencing many SAMSESTs also indicated that there were several SAMS isoforms encoded by thesoybean genome.

A soybean cDNA clone designated s2.12b06 was found to encode a proteinwhich is very similar to the protein encoded by the cDNA to Oryza sativaSAMS (pLog value for this match was 61.59). The soybean cDNA clonedesignated s2.12b06 was completely sequenced (SEQ ID NO:1) and found tocontain an opening reading frame which encodes a full length SAMSpolypeptide. Southern hybridization analysis of soybean genomic DNA withthis full length SAMS cDNA as a probe suggested that there areapproximately four related SAMS genes in the soybean genome (FIG. 1A),which is consistent with the EST sequencing data.

The soybean SAMS cDNA clone was used to isolate a soybean genomic DNAfragment containing more than 2000 nucleotides upstream (5′) of the SAMSprotein coding sequence by hybridization of a soybean genomic DNAlibrary to the SAMS cDNA fragment probe. Southern hybridization analysisof soybean genomic DNA using a 1314 base pair DNA fragment from upstreamof the SAMS protein coding sequence as a probe indicated that thisfragment is unique in the soybean genome (FIG. 1B).

The promoter activity of the soybean genomic DNA fragment upstream ofthe SAMS protein coding sequence was assessed by linking the fragment toa reporter gene, the E. coli β-glucuronidase gene (GUS) (Jefferson(1987) Plant Mol. Biol. Rep. 5:387-405), transforming the SAMSpromoter::GUS expression cassette into Arabidopsis, and analyzing GUSexpression in various cell types of the transgenic plants. GUSexpression was detected in all parts of the transgenic plants that wereanalyzed. These results indicated that the nucleic acid fragmentcontained a constitutive promoter. Since SAMS catalyzes the reaction tosynthesize S-adenosyl-L-methionine from methionine and ATP, freemethionine levels might regulate SAMS promoter activity. To see if theSAMS promoter is regulated by external methionine, the SAMS::GUStransgenic Arabidopsis seeds were germinated in the presence or absenceof methionine. Ten day old seedlings were analyzed for GUS activityaccording to the protocol described in Example 5. Ten independenttransgenic lines were tested and all of them responded similarly. GUSactivity was more than two-fold higher in seedlings germinated in thepresence of methionine (FIG. 8). The increased SAMS promoter activity inthe presence of methionine may be particularly useful for efforts toincrease methionine biosynthesis via overexpression of enzymes in themethionine biosynthetic pathway or the sulfate assimilation pathway. Itis clear from the disclosure set forth herein that one of ordinary skillin the art could readily isolate a constitutive plant SAMS promoter fromany plant by performing the following procedure:

-   -   1) obtaining a SAMS cDNA from a desired plant by any of a        variety of methods well known to those skilled in the art        including, but not limited to, (a) random sequencing of ESTs        from a cDNA library and characterizing the ESTs via a BLAST        search as described above; or (b) hybridizing a cDNA library to        a known plant SAMS cDNA; or (c) PCR amplification using        oligonucleotide primers designed from known SAMS cDNAs;    -   2) obtaining a genomic DNA fragment that includes approximately        500 to 3000 nucleotides from the region 5′ to a SAMS protein        coding sequence, which contains a SAMS promoter, by        hybridization of a genomic DNA library to a SAMS cDNA fragment        probe;    -   3) operably linking the nucleic acid fragment containing the        region upstream (5′) of the SAMS protein coding sequence to a        suitable reporter gene; there are a variety of reporter genes        that are well known to those skilled in the art, including the        bacterial GUS gene, the firefly luciferase gene, and the green        fluorescent protein gene; any gene for which an easy an reliable        assay is available can serve as the reporter gene    -   4) transforming a chimeric SAMS promoter::reporter gene        expression cassette into an appropriate plant for expression of        the promoter. There are a variety of appropriate plants which        can be used as a host for transformation that are well known to        those skilled in the art, including the dicots, Arabidopsis,        tobacco, soybean, oilseed rape, peanut, sunflower, safflower,        cotton, tomato, potato, cocoa and the monocots, corn, wheat,        rice, barley and palm. The terms “oilseed rape” and “oilseed        Brassica” are used interchangeably herein.    -   5) testing for expression of a SAMS promoter in various cell        types of transgenic plants, e.g., leaves, roots, flowers, seeds,        transformed with the chimeric SAMS promoter::reporter gene        expression cassette by assaying for expression of the reporter        gene product. A constitutive SAMS promoter will produce high        level expression of the reporter in all, or nearly all, of the        plant tissues tested.

In another aspect, this invention concerns a chimeric gene comprising atleast one heterologous nucleic acid fragment operably linked to thepromoter of the present invention. Chimeric genes can be constructed byoperably linking the nucleic acid fragment of the invention, i.e., theSAMS promoter or a fragment or a subfragment that is substantiallysimilar and functionally equivalent to any portion of the nucleotidesequence set forth in SEQ ID NOS:6, 14, 15 or 16, to a heterologousnucleic acid fragment. Any heterologous nucleic acid fragment can beused to practice the invention. The selection will depend upon thedesired application or phenotype to be achieved. The various nucleicacid sequences can be manipulated so as to provide for the nucleic acidsequences in the proper orientation.

Plasmid vectors comprising the instant chimeric genes can then beconstructed. The choice of plasmid vector is dependent upon the methodthat will be used to transform host cells. The skilled artisan is wellaware of the genetic elements that must be present on the plasmid vectorin order to successfully transform, select and propagate host cellscontaining the chimeric gene.

The plasmid vectors or chimeric genes can be used to transform plantcells. Transformation techniques are well known to those skilled in artas discussed above. A preferred method of plant cell transformation isthe use of particle-accelerated or “gene gun” transformation technology(Klein et al. (1978) Nature (London) 327:70-73; U.S. Pat. No.4,945,050). The chimeric gene will normally be joined to a marker forselection in plant cells. The particular marker employed will be onewhich will allow for selection of transformed cells as compared to cellslacking the heterologous nucleic acid sequence which has beenintroduced. Examples of plant cells which can be transformed using planttransformation techniques include, but are not limited to, monocot anddicot plant cells such as soybean, oilseed Brassica species, corn,peanut, rice, wheat, sunflower, safflower, cotton, cocoa, tobacco,tomato, potato, barley, palm, Arabidopsis and the like.

In addition to the bacterial GUS gene, two soybean genes, ATPsulfurylase (ATPS) and cystathionine-γ-synthase 1 (CGS1), were alsosuccessfully expressed by this promoter in transgenic Arabidopsis, asdepicted in FIG. 7. This further validates the application of the SAMSpromoter of the invention in plant genetic engineering practice.

The skilled artisan will also recognize that different independenttransformation events will result in different levels and patterns ofexpression of the chimeric genes (Jones et al., (1985) EMBO J.4:2411-2418; De Almeida et al., (1989) Mol. Gen. Genetics 218:78-86).Thus, multiple events must be screened in order to obtain linesdisplaying the desired expression level and pattern. Such screening maybe accomplished by northern analysis of mRNA expression, westernanalysis of protein expression, or phenotypic analysis. Also of interestare seeds obtained from transformed plants displaying the desiredexpression profile.

The level of activity of the SAMS promoter is comparable to that of manyknown strong promoters, such as the CaMV 35S promoter (Atanassova etal., (1998) Plant Mol. Biol. 37:275-285; Battraw and Hall, (1990) PlantMol. Biol. 15:527-538; Holtorf et al., (1995) Plant Mol. Biol.29:637-646; Jefferson et al., (1987) EMBO J. 6:3901-3907; Wilmink etal., (1995) Plant Mol. Biol. 28:949-955), the Arabidopsis oleosinpromoters (Plant et al., (1994) Plant Mol. Biol. 25:193-205; Li, (1997)Texas A&M University Ph.D. dissertation, pp. 107-128), the Arabidopsisubiquitin extension protein promoters (Callis et al., 1990), a tomatoubiquitin gene promoter (Rollfinke et al., 1998), a soybean heat shockprotein promoter (Schoffl et al., 1989), and a maize H3 histone genepromoter (Atanassova et al., 1998).

Expression of the chimeric genes in most plant cell makes the SAMSpromoter of the instant invention especially useful when constitutiveexpression of a target heterologous nucleic acid fragment is required.Examples of suitable target heterologous nucleic acid fragments include,but are not limited to, a herbicide-resistance or pathogen-resistancenucleic acid fragment. Three classes of herbicides, the sulfonylureas,triazolo-pyrimidine sulfonamides, and imidazolinone herbicides, inhibitgrowth of some bacteria, yeast and higher plants by blockingacetolactate synthase [ALS, EC 4.1.3.18]. These three classes ofherbicides are referred to as “inhibitors of ALS”. ALS is the firstcommon enzyme in the biosynthesis of the branched-chain amino acidsvaline, leucine and isoleucine. Mutations in ALS have been identifiedthat convey resistance to some or all of these three inhibitors of ALS(U.S. Pat. No. 5,013,659; the entire contents of which are hereinincorporated by reference). Sulfonylureas are described in the followingU.S. Pat. Nos. 4,127,405; 4,169,719; 4,190,432; 4,214,890; 4,225,337;4,231,784; 4,257,802; 4,310,346; 4,544,401; 4,435,206; 4,383,113;4,394,153; 4,394,506; 4,420,325; 4,452,628; 4,481,029; 4,586,950;4,514,212; 4,634,465; and in EP-A-204,513. Triazolopyrimidinesulfonamides are described in South African Application 84/8844,published May 14, 1985. Imidazolinones are described in U.S. Pat. No.4,188,487; and in EP-A-41,623, published Dec. 16, 1981. Two ALS genes intobacco have been identified and are called SURA (or ALS I) and SURB (orALS II). A double-mutant of the SURB gene in tobacco was generated, thatconveys high-level resistance to inhibitors of ALS, and was designatedHra. The corresponding mutant ALS gene, designated SURB-Hra gene,encodes a herbicide-resistant ALS with the following two mutations inthe amino acid sequence of the protein: the proline at position 191, inthe conserved “subsequence B”, G-Q-V-P (SEQ ID NO:31), has been changedto alanine; and the tryptophan at position 568, in the conserved“subsequence F”, G-M-V-V/M-Q-W-E-D-R-F (SEQ ID NO:32), has been changedto leucine (U.S. Pat. No. 5,013,659; Lee et al. (1988) EMBO J7:1241-1248). A single mutation in a Brassica napus ALS gene has beenidentified that conveys resistance to sulfonylureas, imidazolinones andtriazolopyrimidines (Hattori et al. (1995) Mol Gen Genet 246:419-425).The mutation in the ALS3 (AHAS3) gene results in a change of tryptophanto leucine in the conserved “subsequence F” region,G-M-V-V/M-Q-W-E-D-R-F (SEQ ID NO:32), which corresponds to one of thetwo mutations contained in the herbicide-resistant SURB-Hra gene.

Another useful feature of the constitutive plant SAMS promoter is itsexpression profile in developing seeds. The SAMS promoter of theinvention is most active in developing seeds at early stages andgradually turns down at later stages. Such activity is indicated by theGUS activity detected in seeds of transgenic Arabidopsis plantscontaining a SAMS::GUS expression cassette as shown in FIGS. 4 and 5.The expression profile of the claimed SAMS promoter is different fromthat of many seed-specific promoters, e.g., seed storage proteinpromoters, which often provide highest activity in later stages ofdevelopment (Chen et al., (1989) Dev. Genet. 10:112-122; Ellerstrom etal., (1996) Plant Mol. Biol. 32:1019-1027; Keddie et al., (1994) PlantMol. Biol. 24:327-340; Plant et al., (1994) Plant Mol. Biol. 25:193-205;Li, (1997) Texas A&M University Ph.D. dissertation, pp. 107-128). Thus,the SAMS promoter will be a very attractive candidate whenoverexpression of a gene in embryos is desired at an early developingstage. For example, it may be desirable to overexpress a gene regulatingearly embryo development or a gene involved in the metabolism prior toseed maturation.

One general application of the SAMS promoter of the invention is toconstruct chimeric genes that can be used in the selection of transgeniccell lines in plant transformation. Currently, many of the selectablemarker genes for plant transformation are under the control of thecauliflower mosaic virus 35S promoter. Since the SAMS promoter of theinvention is active in seedlings and callus, the appropriate selectionphase for transgenic plants or cell lines, this promoter may be used asan alternative to the 35S promoter to drive the expression of selectablemarker genes.

Another general application of the SAMS promoter of the invention is toconstruct chimeric genes that can be used to reduce expression of atleast one heterologous nucleic acid fragment in a plant cell. Toaccomplish this a chimeric gene designed for cosuppression of aheterologous nucleic acid fragment can be constructed by linking thefragment to the SAMS promoter of the present invention. (See U.S. Pat.No. 5,231,020 for methodology to block plant gene expression viacosuppression.) Alternatively, a chimeric gene designed to expressantisense RNA for a heterologous nucleic acid fragment can beconstructed by linking the fragment in reverse orientation to the SAMSpromoter of the present invention. (See U.S. Pat. No. 5,107,065 formethodology to block plant gene expression via antisense RNA.) Eitherthe cosuppression or antisense chimeric gene can be introduced intoplants via transformation. Transformants wherein expression of theheterologous nucleic acid fragment is decreased or eliminated are thenselected.

This invention also concerns a method of increasing or decreasing theexpression of at least one heterologous nucleic acid fragment in a plantcell which comprises:

-   -   (a) transforming a plant cell with the chimeric genes described        herein;    -   (b) growing fertile plants from the transformed plant cell of        step (a);    -   (c) selecting plants containing a transformed plant cell wherein        the expression of the heterologous nucleic acid fragment is        increased or decreased.

Transformation and selection can be accomplished using methodswell-known to those skilled in the art including, but not limited to,the methods described herein.

EXAMPLES

The present invention is further defined in the following Examples. Fromthe above discussion and these Examples, one skilled in the art canascertain the essential characteristics of this invention, and withoutdeparting from the spirit and scope thereof, can make various changesand modifications of the invention to adapt it to various usages andconditions.

Unless otherwise stated, all parts and percentages are by weight anddegrees are Celsius. Techniques in molecular biology were typicallyperformed as described in Ausubel, F. M., et al., (1990, CurrentProtocols in Molecular Biology, John Wiley and Sons, New York) orSambrook, J. et al., (1989, Molecular cloning—A Laboratory Manual,2^(nd) ed. Cold Spring Harbor Laboratory Press, Cold Spring Harbor,N.Y.).

Example 1 Composition of cDNA Libraries; Isolation and Sequencing ofcDNA Clones

cDNA libraries representing mRNAs from soybean tissues were prepared inUni-ZAP XR™ vectors according to the manufacturer's protocol(Stratagene, La Jolla, Calif.). Conversion of the Uni-ZAP XR™ librariesinto plasmid libraries was accomplished according to the protocolprovided by Stratagene. Upon conversion, cDNA inserts were contained inthe plasmid vector pBluescript™ (Stratagene). DNA was prepared forsequencing from randomly selected bacterial colonies containingrecombinant pBluescript™ plasmids either by amplifying the cDNA insertsvia polymerase chain reaction using primers specific for vectorsequences flanking the cloning site or by preparing plasmid DNA fromcultured bacterial cells. Amplified insert DNAs or plasmid DNAs weresequenced in dye-primer sequencing reactions using a Perkin Elmer Model377 fluorescent sequencer to generate partial cDNA sequences termedexpressed sequence tags or “ESTs” (see Adams, M. D. et al., (1991)Science 252:1651).

Example 2 Identification of SAMS cDNA Clones

ESTs encoding SAMS were identified by conducting BLAST (Basic LocalAlignment Search Tool; Altschul, S. F., et al., (1993) J. Mol. Biol.215:403-410) searches for similarity to sequences contained in the BLAST“nr” database (comprising all non-redundant GenBank CDS translations,sequences derived from the 3-dimensional structure Brookhaven ProteinData Bank, the last major release of the SWISS-PROT protein sequencedatabase, EMBL, and DDBJ databases). The cDNA sequences obtained inExample 1 were analyzed for similarity to all publicly available DNAsequences contained in the “nr” database using the BLASTN algorithmprovided by the National Center for Biotechnology Information (NCBI).The DNA sequences were translated in all reading frames and compared forsimilarity to all publicly available protein sequences contained in the“nr” database using the BLASTX algorithm (Gish, W. and States, D. J.(1993) Nature Genetics 3:266-272 and Altschul, S. F., et al. (1997)Nucleic Acids Res. 25:3389-3402) provided by the NCBI. For convenience,the P-value (probability) of observing a match of a cDNA sequence to asequence contained in the searched databases merely by chance ascalculated by BLAST are reported herein as “pLog” values, whichrepresent the negative of the logarithm of the reported P-value.Accordingly, the greater the pLog value, the greater the likelihood thatthe cDNA sequence and the BLAST “hit” represent homologous proteins.

The BLASTX search using the nucleotide sequence from clone s2.12b06revealed that this nucleotide sequence encoded a protein that wassimilar to the protein encoded by the cDNA to Oryza sativa (EMBLAccession No. Z26867) S-adenosylmethionine synthetase; the pLog valuefor this match was 61.59. This cDNA clone was completely sequenced (SEQID NO:1) and found to contain an opening reading frame ranging fromnucleotides 74 to 1252 which is predicted to encode a full length SAMSpolypeptide.

A high level of expression of the SAMS genes was inferred by the highfrequency of occurrences of soybean cDNA sequences with homology toOryza sativa SAMS obtained from many different cDNA libraries preparedfrom many different soybean cell types. SAMS homologs were the thirdmost abundant class of ESTs found in the soybean libraries. Although theranking might not represent a precise estimate of the relative abundanceof the SAMS transcripts in vivo in all soybean libraries, due to theselective use of different cDNA libraries, it did indicate that SAMS wasa highly expressed gene. The EST sequence data also revealed that therewere several SAMS isoforms in the soybean genome.

Example 3 5-adenosylmethionine Synthetase is Encoded by a Gene Family

Southern hybridization analysis of soybean genomic DNA with a fulllength SAMS cDNA (SEQ ID NO:1) as a probe suggested that there are atleast four related SAMS genes in the soybean genome (FIG. 1A). The DNAprobe for Southern hybridization was prepared as follows: plasmid DNAwas prepared from an overnight bacteria culture in LB broth (GIBCO BRL,Gaithersburg, Md.) using QIAprep™ miniprep kit (Qiagen, Valencia,Calif.); cDNA inserts encoding SAMS were excised by restriction enzymedigestion and recovered from agarose gel following electrophoreticseparation using QIAquick™ gel extraction kit (Qiagen). The 1518 bp SAMScDNA fragment (SEQ ID NO:1) was labeled with digoxigenin-dUTP as a probeby random primed DNA labeling (Boehringer Mannheim). Twenty microgramsof soybean geneomic DNA was digested with different restriction enzymesand the resulted fragments were resolved on a 0.7% agarose gel. The DNAgel was depurinated in 0.25 M HCl, denatured in 0.5 M NaOH/1.5 M NaCl,neutralized in 1 m Tris-Cl, pH 8.0/1.5 M NaCl, and transferred in 20×SSC(GIBCO BRL) to nylon membrane (Boehringer Mannheim). The Southern blotwas hybridized with the SAMS cDNA-specific probe at 45° C. overnight inEasy Hyb (Roche Diagnostics Corp.). The blot was washed 10 minutes in2×SSC/0.1% SDS, and 3×10 minutes in 0.1×SSC/0.1% SDS at 65° C. Thehybridized probe was detected with chemiluminescent reagent CDP-Star(Boehringer Mannheim) according to the manufacturer's protocol. Multiplebands were detected in BamHI, EcoRI, and HindIII digestions (FIG. 1A).The large band in KpnI and SacI digestions may represent more than oneDNA fragment because the band is too big for good resolution. Thehybridization patterns presented in FIG. 1A and the analysis of partialSAMS cDNA sequences from DuPont's EST database suggest that there are atleast four copies of the SAMS gene in the soybean genome and that theirsequences are conserved.

The 1314 bp SAMS promoter fragment (SEQ ID NO:6) was labeled withdigoxigenin-dUTP also by random primed DNA labeling (BoehringerMannheim). The labeled SAMS promoter probe was used to hybridize thesame Southern blot as above described. The SAMS promoter-specific probehybridized to a single band in each of the five different digestions,BamHI, EcoRI, HindIII, KpnI, and SacI (FIG. 1B). The results indicatethat the SAMS promoter has only a single copy in soybean genome.

A northern hybridization experiment indicated that SAMS gene transcriptswere present in a variety of soybean tissues and that the abundance ofSAMS gene transcripts did not differ greatly from tissue to tissue.Total RNAs were extracted from soybean leaves, stems, young seeds,medium seeds, old seeds, and pod coats using Trizol™ Reagent accordingto the manufacturer's protocol (GIBCO BRL). Ten micrograms of total RNAwere loaded in each well of a 1.2% agarose gel containing 7%formaldehyde in 1×MOPS buffer, 20 mM 3-[N-morpholino]propane-sulfonicacid, 5 mM sodium acetate, 1 mM EDTA, pH 6.0. RNA was transferred tonylon filters (Micron Separations Inc., Westborough, Mass.) in 10×SSCand crosslinked to the filters with UV light. Filters were hybridizedwith probes prepared from cDNA insert fragments in 50% deionizedformamide, 5×SSPE, 1×Denhardt's solution, 0.1% SDS, and 100 μg denaturedsalmon sperm DNA (Sigma, St. Louis, Mo.) at 42° for 24 hours. Filterswere washed in 2×SSPE and 0.1% SDS at room temperature for 10 minutes,1×SSPE and 0.1% SDS at 65° for 10 minutes, and then in 0.1×SSPE and 0.1%SDS at 65° for 10 minutes. Filters were exposed to Kodak X-ray film at−80. The abundance of SAMS transcripts in leaves, roots, stems, youngseeds, medium seeds, old seeds, and pod coats can be seen in FIG. 9. Theweak signals observed in the hybridizations to RNA samples from root andyoung seed were attributed to underloading, because hybridizations withribosomal RNAs that serve as internal controls were also relatively weakin those samples (data not shown). Because of the high sequencesimilarities among the four SAMS gene isoforms, this RNA gel blot wasnot able to indicate how the isoforms were distributed in any particulartissue. However, the experiment demonstrated that all examined soybeantissues contained SAMS messenger RNA.

Example 4 Cloning of the Soybean S-Adenosylmethionine Synthetase GenePromoter

The soybean full length SAMS cDNA (SEQ ID NO:1), obtained in Example 2,was used to generate a probe to isolate a SAMS promoter. The full lengthSAMS cDNA sequence consisted of 1518 bp, and it had a 73 bp5′-untranslated region and a PstI site at position 296. Because the cDNAclone was harbored in a pBluescript™ SK vector having a PstI siteupstream of the EcoRI cloning site, digestion of the clone with Pst1generated a 315 bp fragment of DNA. The resulting restriction fragmentcontained 19 bp of vector and cloning linker adapter sequence inaddition to the 296 bp of SAMS cDNA sequence. This PstI fragment waslabeled with α-³²P-dCTP, as described in Example 3, and used as a probeto screen a soybean genomic DNA library that had been constructed in aEMBL3 SP6/T7 vector (ClonTech, Palo Alto, Calif.). The library wasplated with LE392 (ClonTech) cells at 50,000 plaque forming units (pfu)per 150 mm NZCYM agar plate (GIBCO BRL). Plaques were transferred toHybond nylon membranes, and the plaque replicas were then denatured andneutralized according to the manufacturer (Amersham Life Science,Arlington Heights, Ill.). The phage DNA was fixed on the membranes byUV-crosslinking (Stratagene). After prehybridization at 65° for 1 hourin 0.5 M NaHPO₄, pH 7.2, 1 mM EDTA, 1% crystalline BSA (Sigma), and 7%SDS, the SAMS 315 bp Pst1 fragment probe was denatured in boiling waterbath for 5 minutes and added to the same hybridization solution, and washybridized at 65° for 24 hours. The membranes were washed in 40 mMNaHPO₄, pH 7.2, 1 mM EDTA, 0.5% crystalline BSA, and 5% SDS for 10minutes at room temperature, and then 3×10 minutes at 65° in 40 mMNaHPO₄, pH 7.2, 1 mM EDTA, and 1% SDS. The membranes were exposed toKodak X-ray film (Sigma) at −80°. Positive SAMS genomic DNA phage cloneswere suspended in SM buffer, 50 mM Tris-Cl, pH 7.5, 100 mM NaCl, 0.2%MgSO₄.7H₂O, and 0.1% gelatin, and purified by a secondary screeningfollowing the same procedure. Twenty three strongly hybridizing plaqueswere identified by the first screening from a total of 3×10⁵ pfu, andfifteen were later purified. DNAs were prepared from two of the purifiedphage clones (Ausubel et al., (1990) pp. 1.13.4-1.13.8), they weredigested with BamHI, ClaI, PstI, and NcoI and prepared for a Southernblot. The blot was hybridized with the SAMS 315 bp PstI fragment probeprepared and used as above. A single positive fragment of clone 1 wasidentified from the ClaI digestion. Since the ClaI restriction site inthe cDNA clone is 843 bp from the 5′ end of the full length cDNA, the2.5 kb ClaI fragment was expected to include about 1.7 kb of DNAupstream of the coding sequence, which was considered sufficient tocontain the SAMS promoter.

The 2.5 kb ClaI genomic DNA fragment was cloned into pBluescript™ KS andthe DNA insert was sequenced. The 3′ end sequence of the genomic DNAfragment was expected to match the 5′ end sequence of SAMS cDNA from the5′ end to the ClaI site at position 843. However, comparison of thegenomic DNA sequence and the cDNA sequence revealed that the twosequences have 192 bp of overlapping sequence starting at position 56and ending at position 247 of the cDNA sequence (SEQ ID NO:1). Thesequence of the 2.5 kb genomic DNA clone downstream of the 192 bpoverlapping region was determined to be derived from the cloning vector,lambda EMBL3 SP6/T7, which contributed 257 bp of sequence to the 3′ endof the 2.5 kb SAMS ClaI fragment including the ClaI cloning site.Therefore, the soybean derived DNA in the 2.5 kb ClaI fragment isdescribed by the 2336 bp DNA sequence shown in SEQ ID NO:2.

The DNA sequence of the genomic DNA in the 192 bp region (fromnucleotide 2145 to the end of the sequence) was very similar to, but didnot match perfectly, the cDNA sequence; there were six base pairmismatches in this region. This was not surprising, because it was knownfrom the experiments described in Example 3 that there is a small familyof SAMS genes in soybean. It was concluded that this genomic clone isnot derived from the same gene from which the cDNA used as the probe wastranscribed. It was also noted that the 53 bp at the 5′ end of the cDNAdid not show any similarity to the genomic sequence upstream of the 191bp overlapping region (FIG. 2).

A BLASTN search of the DuPont soybean EST database using the nucleotidesequence from the soybean SAMS genomic DNA upstream of the 192 bp regionrevealed many cDNA clones that matched a 60 bp region of the genomic DNAfrom nucleotide 1496 to 1555. The sequence of one such cDNA, designatedsrr1c.pk002.b21, is shown in SEQ ID NO:3.

The cDNA sequence in SEQ ID NO:3 perfectly matches the genomic sequencein SEQ ID NO:2 from nucleotide 1 to 59 of the cDNA. There follows aregion of 591 nucleotides in the genomic DNA that is absent from thecDNA. Then the region from nucleotide 60 to 249 of the cDNA perfectlymatches the 190 bp region at the 3′ end of the genomic DNA. Thisindicates the presence of a 591 nucleotide intron in the genomic DNA inthe 5′ transcribed, but untranslated, region of the SAMS gene. Thepresence of consensus 5′ and 3′ splice junctions in the genomic DNA atthe exon-intron junctions supports this conclusion. Thus, the 53 bp atthe 5′ end of the cDNA used as the probe (SEQ ID NO:1) did not match thegenomic sequence because the genomic sequence at that position in thealignment was from the intron. However, the 53 bp at the 5′ end of thecDNA of SEQ ID NO:1 is very similar to the 60 nucleotides at the 5′ endof the cDNA of SEQ ID NO:3, suggesting that the gene from which SEQ IDNO:1 was transcribed also contains an intron at the analogous position.

A 1305 bp SAMS genomic DNA fragment starting at nucleotide 856 andending at nucleotide 2160 of SEQ ID NO:2: was amplified by PCR from the2.5 kb ClaI clone. The promoter fragment was amplified from thisfragment using primers sam-5 (SEQ ID NO:4) and sam-6 (SEQ ID NO:5) andPfu DNA polymerase (Stratagene).

CATGCCATGGTTATACTTCAAAAACTGCAC (SEQ ID NO: 4) GCTCTAGATCAAACTCACATCCAA(SEQ ID NO: 5)An XbaI site and an NcoI site were introduced to the 5′ end and 3′ end,respectively, of the PCR fragment by using these specifically designedprimers. The NcoI site includes the ATG start codon of the SAMS codingregion. The resulting 1314 bp fragment is shown in SEQ ID NO:6 andincludes the SAMS promoter and the translation leader region, which isinterrupted by the 591 nucleotide intron. The first three nucleotides ofSEQ ID NO:6 originate from the linker DNA. The first nucleotide of thecDNA sequence presented in SEQ ID NO:3 corresponds to nucleotide number645 in SEQ ID NO:6.

Using PCR amplification procedures and appropriate primers additionalSAMS promoter fragments can be produced from the 2336 nucleotidefragment of SEQ ID NO:2. These include, but are not limited to, thethree fragments provided in SEQ ID NOs:14, 15 and 16. SEQ ID NO:14 is a2165 nucleotide sequence of a SAMS promoter DNA fragment which starts atthe 5′ end of the 2336 nucleotide sequence of SEQ ID NO:2 and ends atthe ATG translation start codon of the SAMS protein. The firstnucleotide of the cDNA sequence presented in SEQ ID NO:3 corresponds tonucleotide number 1497 in SEQ ID NO:14. SEQ ID NO:15 is a 1574nucleotide sequence of a SAMS promoter DNA fragment which starts at the5′ end of the 2336 nucleotide sequence of SEQ ID NO:2 and ends at theATG translation start codon of the SAMS protein, and from which the 591nucleotide long intron sequence has been removed. SEQ ID NO:16 is a 719nucleotide sequence of a SAMS promoter DNA fragment which starts atnucleotide 4 of SEQ ID NO:6 and ends at the ATG translation start codonof the SAMS protein, and from which the 591 nucleotide long intronsequence has been removed.

Example 5 Expression of the GUS Gene by the SAMS Promoter in Arabidopsis

The activity of the soybean SAMS promoter was tested by its ability toexpress the GUS reporter gene in transgenic Arabidopsis plants carryingthe SAMS promoter:GUS::3′ Nos expression casstette. GUS refers to the E.coli β-glucuronidase gene (GUS) (Jefferson, (1987) Plant Mol. Biol. Rep.5:387-405) and 3′ Nos refers to the transcription termination regionfrom the nopaline synthase (Nos) gene (Depicker et al. (1982) J. Mol.Appl. Genet. 1:561-570). The SAMS promoter fragment (SEQ ID NO:6) wasdigested with XbaI and NcoI and inserted into plasmid pMH40Δ (SEQ IDNO:17), which contained a 35S promoter::GUS::3′ Nos plant expressioncassette. The XbaI/NcoI SAMS promoter DNA fragment replaced the ³⁵Spromoter of pMH40Δ, to form the pZSL11 plasmid (FIG. 3). The SAMSpromoter:GUS::3′ Nos DNA fragment (SEQ ID NO:18) was excised from pZSL11bp HindIII and SacI digestion and transferred into the correspondingsites of pBI101 (ClonTech) binary vector. The cloned SAMS promoter wassequenced to verify that no sequence error was generated by the PCRamplification.

The SAMS::GUS expression cassette was introduced into wild typeArabidopsis thaliana by Agrobacteria mediated transformation. A.thaliana ecotype columbia were grown in 228 chamber with continuouslight and transformed by vacuum infiltration method using GV3101Agrobacteria (Bent, A. et al., (1994) Science 265:1856-1860).Transformed Arabidopsis seeds were selected by germination on Murashigeand Skoog minimal salt (GIBCO BRL) plus 0.2% phytagel (Sigma), 1%sucrose, and 100 mg/ml kanamycin. The kanamycin resistant seedlings weretransferred into soil and grown in 228 chamber under continuous light.

For histochemical GUS staining, plant tissues were incubated in 0.5%5-bromo-4-chloro-3-indoxyl-β-D-glucuronic acid (X gluc, Biosynth AG,Switzerland) in 50 mM sodium phosphate, pH 7.0, 10 mM EDTA, 0.5 mMpotassium ferricyanide, and 0.5 mM potassium ferrocyanide at 378overnight, and then chlorophyll was removed with 75% ethanol. Pictureswere taken using a Nikon dissecting microscope. Strong GUS expressionwas detected in all the parts of the transgenic Arabidopsis plants,including flowers (FIG. 4A), leaves (FIG. 4B), stems (bolt) (FIG. 4C),silique coats and developing seeds (FIG. 4D-F), developing embryos (FIG.4G), and seedlings (not shown). The GUS staining on leaves and siliquecoats was uniform with all the veins and mesophyll tissues similarlystained, while staining on flowers and stems was not uniform. Althoughsome seeds were not stained for GUS activity due to genetic segregation,the funiculi that connected these seeds to the silique coat stainedpositively for GUS activity (FIG. 4G). These results indicated that thesoybean SAMS promoter was a constitutive promoter and was able tofunction in heterologous plant.

The GUS activities of the transgenic Arabidopsis plants were furtheranalyzed by a fluorometric assay. For fluorescence analysis, planttissues were ground in microfuge tubes with extraction buffer, 50 mMphosphate buffer, pH 7.0, 10 mM EDTA, 0.1% Triton X-100, 0.1% N-lauroylsarcosine, and 10 mM β-mercaptoethanol, to homogeneity. The samples werecentrifuged at 14,000 rpm for 10 minutes, and aliquots of thesupernatant were used to determine protein concentrations by theBradford method (Bio-Rad, Hercules, Calif.) using 96 well microtiterplates read with a kinetic microplate reader (Molecular Devices,Sunnyvale, Calif.). The β-glucuronidase activities were analyzed bystandard protocol (Jefferson et al, (1987) EMBO J. 6:3901-3907) using 96well microtiter plates read with Cytofluor multiwell plate reader(PerSeptive Biosystems, Framingham, Mass.). Data were entered into aMicrosoft Excel spread sheet and analyzed. Triple samples of flower,leaf, stem, silique coat, young seed (white), medium seed (light green),old seed (dark green), and dry seed from six plants were analyzed. Thesoybean SAMS promoter was active in all the tissues analyzed (FIG. 5).Promoter activity varied among the six lines, as is typically seen amongplant transformants. The basic expression patterns were similar amongall the lines, and the average SAMS promoter activity was comparable tothat of the 35S promoter (Battraw and Hall, (1990) Plant Mol. Biol.15:527-538; Jefferson et al., (1987) EMBO J. 6:3901-3907; Atanassova etal., (1998) Plant Mol. Biol. 37:275-285; Holtorf et al., (1995) PlantMol. Biol. 29:637-646; Wilmink et al., (1995) Plant Mol. Biol.28:949-955). The SAMS promoter was very active in developing seeds,especially in early and medium stages of development, and the GUSspecific activities are in the range of 5-40 pmole 4-Mu(4-methylumbelliferone) per microgram protein per minute, which arecomparable to many strong promoters (Atanassova et al., (1998) PlantMol. Biol. 37:275-285; Comai et al., (1990) Plant Mol. Biol. 15:373-381;Holtorf et al., (1995) Plant Mol. Biol. 29:637-646; Wilmink et al.,(1995) Plant Mol. Biol. 28:949-955).

Example 6 Expression of GUS Gene by SAMS Promoter in Corn

In order to test whether the dicot SAMS promoter also worked in monocotplants, pZSL11 was introduced into corn leaf discs and callus by genebombardment for transient gene expression assay using the biolisticparticle delivery system PDS-1000/He (Bio Rad, Hercules, Calif.). ThepMH40Δ plasmid DNA (as set forth in SEQ ID NO:17), which contained the35S promoter and GUS reporter gene, was also introduced into corn callusand leaf discs by gene bombardment to serve as a positive controlvector. After incubation overnight at 37°, bombarded tissues werestained for GUS activity. GUS expression was demonstrated by the bluespots on both the callus (FIG. 6A) and leaf discs (FIG. 6B) bombardedwith pZSL11. As expected, the positive control 35S::GUS cassette wasalso expressed in both callus and leaf discs (FIGS. 6C, D).

Example 7 Expression of Methionine Biosynthesis Genes by SAMS Promoter

The SAMS promoter was fused to two soybean cDNAs, one encoding ATPsulfurylase (ATPS) and a second encoding cystathionine-γ-synthase(CGS1). The soybean ATPS and CGS1 cDNAs were isolated from soybeanembryo cDNA libraries using the same procedures as described in Example1 and Example 2 for isolation of soybean SAMS cDNAs. The coding regionsand the 3′ untranslated region (UTR) of soybean ATPS and CGS1 genes wereinserted into pZSL11 replacing the GUS gene. The resulting SAMSpromoter::ATPS and SAMS promoter::CGS1 expression cassettes, SEQ IDNO:19 and SEQ ID NO:20, respectively, were inserted into binary vectorsfor Arabidopsis transformation and transformation was performed asdescribed in Example 5. Transgenic Arabidopsis plants with soybean ATPSand CGS1 genes controlled by the SAMS promoter were analyzed by PCR forthe presence of the transgenes and by RT-PCR for expression of thetransgenes. Genomic DNA used for PCR analysis was prepared fromArabidopsis siliques and leaves using 7 M urea, 1.5 M NaCl, 50 mM Tris,pH 8.0, mM EDTA, and 1% N-lauroyl-sarcosine, followed by phenolextraction and ethanol precipitation. Primer sam-9 (SEQ ID NO:7) whichis specific to SAMS promoter, and primers specific to the target genes,atps-1 (SEQ ID NO:8) for the ATPS gene and cgs-8 (SEQ ID NO:9) for theCGS1 gene were used in PCR with Taq DNA polymerase (GIBCO BRL) to detectthe existence of SAMS::ATPS and SAMS::CGS1 in transgenic Arabidopsisplants.

TTCGAGTATAGGTCACAATAGG (SEQ ID NO: 7) CTTCGCTGAGGACATGGAC (SEQ ID NO: 8)GAGTTGTCGCTGTTGTTCGAC  (SEQ ID NO: 9)

RNA samples used for RT-PCR were prepared with Trizol™ Reagent (GIBCOBRL). Antisense primers atps-4 (SEQ ID NO:10) and cgs-10 (SEQ ID NO:11)were used in reverse transcription reactions with SuperscriptII™ RT(GIBCO BRL) following the vendor's instruction.

AACACAGCATCCGCATTGCG (SEQ ID NO: 10) AGGAGTGCAGAATCAGATCAG(SEQ ID NO: 11)The first strand cDNAs were used in PCR with primer pairs atps-3 (SEQ IDNO:12) and atps-4 (SEQ ID NO:10) for SAMS::ATPS transgenic plants, andcgs-9 (SEQ ID NO:13) and cgs-10 for SAMS::CGS1 transgenic plants. PCRand RT-PCR products were resolved by agarose gel electrophoresis.

GCTGATCGAACCAGATGGAG (SEQ ID NO: 12) CTGTACAGTTAAACAGTAGTTCT(SEQ ID NO: 13)

All ten SAMS::CGS1 transgenic Arabidopsis harbored the SAM::CGS1expression cassette as revealed by PCR with SAMS::CGS1-specific primers(FIG. 7A). It was also revealed by the same analysis that all the tenSAMS::ATPS transgenic Arabidopsis plants contained the SAMS::ATPSexpression cassette (FIG. 7A). RT-PCR analysis detected CGS1 transcriptsand ATPS transcripts, respectively, in most of the transgenic plants(FIG. 7B). This shows that the SAMS promoter is capable of drivingexpression of a variety of different genes in most or all cell types intransformed plants.

Example 8 Induction of SAMS Promoter Activity by Methionine

Since SAMS catalyzes the reaction to synthesize S-adenosyl-L-methioninefrom methionine and ATP, free methionine levels might regulate SAMSpromoter activity. To see if SAMS promoter is regulated by externalmethionine, the SAMS::GUS transgenic Arabidopsis seeds were germinatedin the presence of either H₂O, 1× Murashige and Skoog salt (GIBCO BRL),0.01 mM methionine (Sigma), or 1 mM methionine. Ten days old seedlingsfrom ten independent transgenic lines were analyzed for GUS activityaccording to the protocol described in Example 5. GUS activity for eachtreatment, in the order given above, for each transgenic line is shownin FIG. 8. All lines responded similarly to the different treatments.Compared to the control of H₂O treatment, SAMS activity was induced morethan two-fold by 0.01 mM free methionine and inhibited about 40% onaverage by 1×MS salt. The induction effect of SAMS promoter by 1 mMmethionine was less than that by 0.01 mM methionine, probably due to atoxic effect of the high methionine concentration; this toxic effect wasindicated by the smaller sizes and shorter roots of the seedlings grownin the presence of 1 mM methionine. The toxic effect of high levels ofmethionine was even more apparent at 10 mM free methionine, since only afew Arabidopsis seeds were able to germinate and none survived in thepresence of 10 mM free methionine.

Example 9 Expression in Soybean by the SAMS Promoter of the GUS Gene andTwo Herbicide-Resistant Acetolactate Synthase Genes

Two different soybean SAMS DNA fragments, containing the nucleotidessequences of SEQ ID NO:6 and 14, were shown to have promoter activity intransgenic soybean cells. The plasmid DNA constructs used are describedin TABLE 1.

TABLE 1 Plasmid DNA SAMS Promoter Coding Region Terminator pZSL11 1.3-kb(SEQ ID NO: 6) GUS NOS pZSL12 2.1-kb (SEQ ID NO: 14*) GUS NOS pZSL131.3-kb (SEQ ID NO: 6) Soybean ALS** Soybean ALS pZSL14 2.1-kb (SEQ IDNO: 14*) Arabidopsis Arabidopsis ALS** ALS *Variant of SEQ ID NO: 14with an NcoI site introduced around the start Met. **Mutant soybean andArabidopsis Acetolactate Synthase (ALS) genes were used, that encode ALSenzymes resistant to herbicidal inhibitors of ALS, such as sulfonylureaherbicides.

Plasmid pZSL11 contains the 1.3-kb SAMS promoter (SEQ ID NO:6) operablylinked to the GUS reporter gene (Jefferson (1987) Plant Mol. Biol. Rep.5:387-405), and the NOS terminator (Depicker et al. (1982) J. Mol. Appl.Genet. 1:561-570). The construction of pZSL11 is described in Example 5of the specification. The nucleotide sequence of the {1.3-kb SAMSpromoter—GUS—NOS} region corresponds to SEQ ID NO:18.

Plasmid pZSL12 was made by replacing the 5′ region of the 1.3-kb SAMSpromoter in pZSL11 with a longer SAMS genomic DNA from pZSL10, a plasmidDNA containing an 2335-bp SAMS genomic DNA cloned in pBluescript KS. The1675-bp XhoI(blunt-ended with E. coli DNA polymerase I Klenowfragment)/BamHI fragment from pZSL10 was transferred into pZSL11, toreplace the corresponding 809-bp XbaI (blunt end with E. coli DNApolymerase I Klenow fragment)/BamHI fragment. The resulting plasmid,pZSL12, has a 2.1-kb SAMS promoter (a variant of SEQ ID NO:14 thatcontains an NcoI site surrounding the start methionine) which is 869-bplonger than the 1.3-kb SAMS promoter in pZSL11. The nucleotide sequenceof the {2.1-kb SAMS promoter—GUS—NOS} region from pZSL12 is shown in SEQID NO:21.

Plasmid pZSL13 was made by replacing the GUS gene and NOS terminator inpZSL11 with a DNA fragment containing a soybean mutant ALS coding regionand its 3′-UTR (UnTranslated Region). The mutant soybean ALS geneencodes an enzyme that is resistant to inhibitors of ALS, such assulfonylurea herbicides. The nucleotide sequence of the {1.3-kb SAMSpromoter—mutant soy ALS—soy ALS 3′-UTR} region in pZSL13 is shown in SEQID NO:22. The corresponding amino acid sequence of the mutant soy ALSprotein is shown in SEQ ID NO:23. Plasmid pZSL14 was made by linking the2.1-kb SAMS promoter from pZSL12 to a DNA fragment containing a mutantArabidopsis ALS gene and its 3′-UTR. The mutant Arabidopsis ALS geneencodes an enzyme that is resistant to inhibitors of ALS, such assulfonylurea herbicides. The nucleotide sequence of the {2.1-kb SAMSpromoter—mutant Arabidopsis ALS—Arabidopsis ALS 3′-UTR} region in pZSL14is shown in SEQ ID NO:24. The corresponding amino acid sequence of themutant Arabidopsis ALS protein is shown in SEQ ID NO:25. Mutant plantALS genes encoding enzymes resistant to sulfonylurea herbicides aredescribed in U.S. Pat. No. 5,013,659 (1991), “Nucleic acid fragmentencoding herbicide resistant plant acetolactate synthase”. One suchmutant is the tobacco SURB-Hra gene, which encodes a herbicide-resistantALS with the following two mutations in the amino acid sequence of theprotein: the proline at position 191, in the conserved “subsequence B”,G-Q-V-P (SEQ ID NO:31), has been changed to alanine; and the tryptophanat position 568, in the conserved “subsequence F”, G-M-V-V/M-Q-W-E-D-R-F(SEQ ID NO:32), has been changed to leucine (U.S. Pat. No. 5,013,659;Lee et al. (1988) EMBO J 7:1241-1248). The mutant soy ALS gene used inpZSL13 was created by introducing the two Hra-like mutations into thewild-type soybean sequence; the proline at position 183 was changed toalanine, and the tryptophan at position 560 was changed to leucine (SEQID NO:23). In addition, during construction of PZSL13, theprotein-coding region of the soybean ALS gene was extended at the 5′-endby five artificial codons, resulting in five amino acids, M-P-H-N-T (SEQID NO:33), added to the amino-terminus of the ALS protein (SEQ IDNO:23). These extra amino acids are adjacent to, and presumably removedwith, the transit peptide during targeting of the mutant soy ALS proteinto the plastid. The mutant Arabidopsis ALS gene used in pZSL13 wascreated by introducing the two Hra-like mutations into the wild-typeArabidopsis sequence; the proline at position 197 was changed toalanine, and the tryptophan at position 574 was changed to leucine (SEQID NO:25). FIGS. 10A-10C show an amino acid sequence alignment of thefollowing herbicide-sensitive wild-type ALS proteins: a tobacco SURB(ALS II) protein (SEQ ID NO:27; NCBI General Identifier No. 124369); aBrassica napus ALS3 (AHAS3) protein (SEQ ID NO:28; NCBI GeneralIdentifier No. 320131); an Arabidopsis thaliana ALS protein (SEQ IDNO:29; NCBI General Identifier No. 124372); and a soybean ALS protein(SEQ ID NO:30).

Soybean transformation was performed as follows:

Soybean embryogenic suspension cultures were transformed with theGUS-containing plasmids, pZSL11 and pZSL12, by the method of particlegun bombardment using procedures know in the art (Klein et al. (1987)Nature (London) 327:70-73; U.S. Pat. No. 4,945,050; Hazel, et al. (1998)Plant Cell Rep 7:765-772; Samoylov, et al. (1998) In Vitro Cell DevBiol—Plant 34:8-13). Alternatively, one can use purified DNA restrictionfragments containing only the recombinant DNA expression cassette(s) ofinterest, using 1-15 pg of DNA fragment per base pair of DNA fragmentper 30 μl prep. Each such prep is enough to do eight transformationbombardments. The selective agent used was hygromycin (50 mg/mL). Inaddition, 0.6 μm gold particles were used instead of 1.0 μm particles.Soybean embryogenic suspension cultures were transformed with plasmidspZSL13 and pZSL14, each containing a mutant ALS gene, by a similarprocedure with the following modifications.

Stock tissue for these experiments were obtained by initiation ofsoybean immature seeds. Secondary embryos were excised from explantsafter 6-8 weeks on media. Secondary embryos were placed on media for 7-9days under ˜80 μEm⁻²s⁻¹ light intensity. Tissue was dried on Whatman #2filter paper then moved to a prebombardment osmotic treatment (mediacontaining 0.25 M mannitol and 0.25 M sorbitol) for 4 hours under ˜80μEm⁻²s⁻¹ light intensity. After 4 hours, tissue was moved to an empty60×15 mm petri dish for bombardment. Approximately 10 mg of tissue(10-15 clumps of 1-2 mm size) were used per plate bombarded.

After bombardment, tissue was moved to media for an overnight incubationat ˜80 μEm⁻²s⁻¹ light intensity. Tissue was divided in half and placedin liquid media for selection. For selection of transformed cellscontaining the mutant ALS gene (pZSL13 and pZSL14), the selective agentused was a sulfonylurea (SU) compound with the chemical name,2-chloro-N-[(4-methoxy-6methyl-1,3,5-triazine-2-yl)aminocarbonyl]benzenesulfonamide (commonnames: DPX-W4189 and chlorsulfuron). Chlorsulfuron is the activeingredient in the DuPont sulfonylurea herbicides, GLEAN®. Theconcentration of SU used was 90 ng/ml. SU was applied one week afterbombardment and continued for six weeks, with a fresh media and SUchange once a week. After six weeks, events were isolated and kept at 90ng/ml concentration for another 4-6 weeks. Total time in SU was 8-12weeks.

After selection, green, transformed tissue was observed growing fromuntransformed, necrotic embryogenic clusters. Isolated green tissue wasremoved and inoculated into individual flasks to generate new, clonallypropagated, transformed embryogenic suspension cultures. Suspensioncultures were subcultured and maintained as clusters of immature embryosand also regenerated into whole plants by maturation and germination ofindividual somatic embryos.

SAMS promoter activity in transgenic soybeans was determined as follows:

Soybean embryogenic suspension cells, transformed with either pZSL11 orpZSL12, were assayed for GUS activity by the histochemical stainingprocedure described in Example 5. From the results of this assay, it wasobserved that both the 1.3-kb (SEQ ID NO:6) and the 2.1-kb (SEQ IDNO:14) fragments from the SAMS gene displayed promoter activity (FIG.11).

Soybean plants were regenerated from embryogenic suspension cellstransformed with either pZSL11 or pZSL12. The results of GUShistochemical staining of pZSL11 transformed soybean tissues(embryogenic suspension cells, leaf, stem and root) are shown in FIG.12. These results indicate promoter activity for the 1.3-kb (SEQ IDNO:4) fragment of pZSL11 in each of these cell types (FIG. 12). Similarresults were obtained for the 2.1-kb (SEQ ID NO:14) fragment of pZSL12.

The 1.3-kb and 2.1-kb SAMS fragments in pZSL13 and pZSL14, respectively,were also used to drive expression of the SU-resistant mutant ALS genesfrom soybean (pZSL13) and Arabidopsis (pZSL14). Transformed soybean celllines were selected using the SU herbicide, as described above.Transgenic soybean cell lines containing either plasmid DNA wereobtained, demonstrating that both SAMS fragments functioned as promotersin embryogenic suspension cells.

Soybean plants, transformed with either pZSL13 or pZSL14, were testedfor tolerance to SU herbicide. A spray solution was made containing 60grams of Thifensulfuron-methyl active ingredient per hectare and 0.25%wt/wt of AL-2999 nonionic surfactant. Thifensulfuron-methyl has thechemical name, methyl3-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]amino]sulfonyl]-2-thiophenecarboxylate,and is the active ingredient in the two DuPont sulfonylurea herbicides,HARMONY GT® and PINNACLE®. Either HARMONY GT® or PINNACLE® can be usedas the source of this sulfonylurea for the spray test. AL-2999 is anonionic surfactant, obtainable as ATPLUS UCL 1007® from Uniqema. Thismixture was evenly sprayed onto the soybean plants at the 1st or 2ndtrifoliate stage of development. After waiting approximately two weeksthe results were scored. All wild-type plants (or plants lacking theSAMS:herbicide-resistant ALS transgene) were dead (negative control),all plants from commercially available STS® (Sulfonylurea TolerantSoybean) seeds were alive (positive control), and plants containing theSAMS:herbicide-resistant ALS transgene from either pZSL13 or pZSL14 alsosurvived. Consequently, either the 1.3-kb (SEQ ID NO:6) or the 2.1-kb(SEQ ID NO:14) fragment from the SAMS gene can drive expression of themutant ALS gene at levels sufficient to provide tolerance to SU.

Both the 1.3-kb (SEQ ID NO:6) and the 2.1-kb (SEQ ID NO:14) fragmentsfrom the SAMS gene functioned as promoters in transgenic soybean.Promoter activity was observed in multiple cell types (embryonicsuspension cells, leaf, stem and root). In addition, promoter activitywas sufficient to drive functional expression of both a screenablemarker (GUS) and a selectable marker (herbicide-resistant ALS) gene.

What is claimed is:
 1. A recombinant DNA construct comprising a firstisolated nucleic acid fragment encoding a polypeptide operably linked toa second isolated nucleic acid fragment selected from the groupconsisting of: a) an isolated nucleic acid fragment comprising thenucleic acid sequence of SEQ ID NO:6; b) an isolated nucleic acidfragment comprising the nucleic acid sequence of SEQ ID NO:14; c) anisolated nucleic acid fragment comprising nucleotides 4-644 of SEQ IDNO:6; d) an isolated nucleic acid fragment comprising nucleotides 1-1496of SEQ ID NO:14; e) an isolated nucleic acid fragment comprising asubfragment of SEQ ID NO:6, wherein the subfragment has constitutivepromoter activity in a plant; f) an isolated nucleic acid fragmentcomprising a subfragment of SEQ ID NO:14, wherein the subfragment hasconstitutive promoter activity in a plant; and g) an isolated nucleicacid fragment, having constitutive promoter activity in a plant, whichhas at least 98% sequence identity, using the Clustal method ofalignment with default parameters GAP PENALTY=10, GAP LENGTH PENALTY=10,KTUPLE=2, GAP PENALTY=5, WINDOW=4 and DIAGONALS SAVED=4, with any of theisolated nucleic acid fragments set forth in (a) through (f).
 2. Therecombinant DNA construct of claim 1 wherein the polypeptide encoded bythe first isolated nucleic acid fragment has an amino acid sequencecomprising SEQ ID NO:23 or SEQ ID NO:25.
 3. A plant, plant cell or planttissue comprising the recombinant DNA construct of claim 1 or claim 2.4. The plant of claim 3 wherein said plant is a dicot.
 5. The plant ofclaim 4 where said plant is a dicot selected from the group consistingof Arabidopsis, soybean, oilseed Brassica, peanut, sunflower, safflower,cotton, tobacco, tomato, potato, and cocoa.
 6. The plant of claim 5wherein said plant is soybean.
 7. A seed comprising the recombinant DNAconstruct of claim 1 or claim
 2. 8. The seed of claim 7, wherein saidseed is from a dicot.
 9. The seed of claim 8, wherein said seed is froma dicot selected from the group consisting of Arabidopsis, soybean,oilseed Brassica, peanut, sunflower, safflower, cotton, tobacco, tomato,potato, and cocoa.
 10. The seed of claim 9, wherein said seed is fromsoybean.
 11. A method for selection of a transformed plant cell havingresistance to at least one inhibitor of acetolactate synthase whichcomprises: (a) transforming a plant cell with the recombinant DNAconstruct of claim 2; (b) growing the transformed plant cell of step (a)in the presence of an effective amount of at least one inhibitor ofacetolactate synthase; and (c) selecting a transformed plant cellwherein said transformed plant cell is resistant to at least oneinhibitor of acetolactate synthase.
 12. The method of claim 11 whereinthe inhibitor of acetolactate synthase is a sulfonylurea herbicide. 13.The method of claim 12 wherein the sulfonylurea herbicide is selectedfrom the group consisting of chlorsulfuron and thifensulfuron-methyl.14. The method of claim 11 wherein the plant cell is from a dicot. 15.The method of claim 12 wherein the plant cell is from a dicot.
 16. Themethod of claim 13 wherein the plant cell is from a dicot.
 17. Themethod of claim 11 wherein the plant cell is from a dicot selected fromthe group consisting of Arabidopsis, soybean, oilseed Brassica, peanut,sunflower, safflower, cotton, tobacco, tomato, potato, and cocoa. 18.The method of claim 12 wherein the plant cell is from a dicot selectedfrom the group consisting of Arabidopsis, soybean, oilseed Brassica,peanut, sunflower, safflower, cotton, tobacco, tomato, potato, andcocoa.
 19. The method of claim 13 wherein the plant cell is from a dicotselected from the group consisting of Arabidopsis, soybean, oilseedBrassica, peanut, sunflower, safflower, cotton, tobacco, tomato, potato,and cocoa.
 20. The method of claim 11 wherein the plant cell is fromsoybean.
 21. The method of claim 12 wherein the plant cell is fromsoybean.
 22. The method of claim 13 wherein the plant cell is fromsoybean.
 23. A method for producing a plant having resistance to atleast one inhibitor of acetolactate synthase which comprises: (a)transforming a plant cell with the recombinant DNA construct of claim 2;(b) growing at least one fertile transformed plant from the transformedplant cell of step (a); and (c) selecting a transformed plant whereinsaid transformed plant is resistant to at least one inhibitor ofacetolactate synthase.
 24. The method of claim 23 wherein the inhibitorof acetolactate synthase is a sulfonylurea herbicide.
 25. The method ofclaim 24 wherein the sulfonylurea herbicide is selected from the groupconsisting of chlorsulfuron and thifensulfuron-methyl.
 26. The method ofclaim 23 wherein the plant is a dicot.
 27. The method of claim 24wherein the plant is a dicot.
 28. The method of claim 25 wherein theplant is a dicot.
 29. The method of claim 23 wherein the plant is adicot selected from the group consisting of Arabidopsis, soybean,oilseed Brassica, peanut, sunflower, safflower, cotton, tobacco, tomato,potato, and cocoa.
 30. The method of claim 24 wherein the plant is adicot selected from the group consisting of Arabidopsis, soybean,oilseed Brassica, peanut, sunflower, safflower, cotton, tobacco, tomato,potato, and cocoa.
 31. The method of claim 25 wherein the plant is adicot selected from the group consisting of Arabidopsis, soybean,oilseed Brassica, peanut, sunflower, safflower, cotton, tobacco, tomato,potato, and cocoa.
 32. The method of claim 23 wherein the plant issoybean.
 33. The method of claim 24 wherein the plant is soybean. 34.The method of claim 25 wherein the plant is soybean.